Speed and velocity

 Sana 09.09.2017 Hajmi 119.5 Kb.
SPEED AND VELOCITY
2. DEFINE: SPEED

VELOCITY

3. Calculate the speed of a horse that goes 400m in 22.4 seconds:
4. A jet is flying at 1200 km per hour. How long will it take to go from New York to Los Angeles (2800 MILES)?
5. How far can a snail get in 30 seconds if it travels at .75 m/min ?

6. At an average sped of 55 MPH, how long will it take to get to Disneyworld, 990 miles away?

7. If it takes 45 minutes to bike the 7.8 miles from Dawson to Layton, what is your average speed in MPH?
8. Now (from #7) compute your speed in meters per second:

SPEED MINI-LAB
The purpose of this activity is to acquaint us with acquiring and processing the data needed to calculate average speed of given objects.
1. Our group will determine the average speed of __________________________________________________.
2. Explain why you are determining AVERAGE speed:

3. We will measure the time it takes our object to go a particular distance. DISTANCE = _______________.

4. We will time the object over this distance a total of 5 times, and record the data below.
5. We will then calculate the speed for each trial, using the formula: ______________.
6. We will then calculate an average AVERAGE SPEED as our “final answer.”

 Trial number Distance (m) Time (s) Average speed (m/s) 1 2 3 4 5 Average Value for Average Speed =

7. Explain two factors (other than human error!!!) that may have caused variation in your answers.

SPEED AND VELOCITY, p. 3
1. Explain the difference between speed and velocity:

2. Indicate whether the following are speeds (S) or velocities (v):

____ 17.4 miles per hour south

____ 142 m/s

____ "as fast as greased lightning"

____ falling at 74 km/hr

____ 75 miles per hour
3. Calculate the speed of a truck that goes 600m in 15.4 seconds:
4. A boat is travelling at 12 km per hour. How long will it take to go from Pittsburgh to East Brady (65 MILES)?

5. How far can a cheetah get in 30 seconds if it travels at 90 km/hr ?

6. At an average speed of 55 MPH, how long will it take to get to Chicago, 500 miles away?
7. If it takes 32 minutes to rollerblade the 6.0 miles from Oil City to Franklin, what is your average speed in MPH?
8. Now (from #7) compute your speed in meters per second:
9. Calculate the speed (in m/s) of a boat that goes 14.5 km in 1.3 hr.
10. A jet is travelling at 550 MPH. How long will it take to go from Pittsburgh to Cancun (2000 kilometers)?

11. How far can a dogsled get in 6.2 minutes if it travels at 15 miles/hr ?

12. At an average speed of 62 MPH, how long will it take to get to Graceland (in Memphis), 1000 kilometers away?
13. If it takes 1 hour and 6 minutes to run the 7.8 miles from Dawson to Layton, what is your average speed in MPH?
14. Now (from #13) compute your speed in meters per second:
15. What is the average speed of the earth, if it completes an orbit of the sun in 365.24 days. The radius of the orbit is 93 million miles. Express your answer in miles per hour.

VELOCITY AND ACCELERATION

1. Define each of the following:
a. speed:

b. velocity:

c. acceleration (definition 1):

d. acceleration (definition 2):

e. "delta v"

2. Indicate whether the following are speeds (S) or velocities (v):

____ 17 000 miles per hour

____ straight up at 14.2 m/s

____ "as slow as molasses in January"

____ flying south at 740 km/hr

____ from Pittsburgh to Buffalo, NY at 62 miles per hour
3. List the three forms of acceleration:
a.
b.
c.
4. Indicate (Y = yes, N = no) if each of the following is acceleration:

____ A car rounding a corner at a constant speed of 70 km/hr.

____ A bobsled speeding up from 0 to 60 miles per hour.

____ A bicyclist traveling on a straight level road at a constant speed

of 22 km/hr.
5. Compute the speed of a motorcycle that travels 650 meters in 11.78s:
6. Compute the acceleration of a bicyclist that accelerates from 5.4 m/s to 8.9 m/s in a time of 4.82s:

7. Compute the acceleration (in m/s2) of a car that goes from 0 to 60 MPH in 7.22s:

8. A Navy fighter plane lands on an aircraft carrier and is caught by a huge cable. It slows from 120.77 miles per hour to a complete stop in 1.92s. Compute it's acceleration in m/s2.

9. "One g" is equivalent to the acceleration due to gravity, which is 9.8m/s2. How many g's is the pilot in #8 subjected to?

10. Compute the acceleration of a truck that slows from 25.4 m/s to 13.7 m/s in a time of 3.72s:

11. A skier is travelling at 3.8 m/s, then heads downhill and accelerates at 2.9 m/s2 for 3.50s. What is the skier's final speed?

12. A falling object accelerates at 10 (actually 9.8) m/s2. Calculate the speed of a rock that has been falling for 4.0 seconds:

LAB – The Effect of Angle on the Average Speed of a Rolling Marble

OBJECTIVE: Determine the relationship of angle of a sloped ramp and the average speed of a marble rolling down that ramp.

Identify: Independent Variable: _______________________ (graph on the _______________ axis)
Dependent Variable: _______________________ (graph on the _______________ axis)

Procedure: Using the ramps and marbles provided, complete the data table below:

Ramp length = _____________________

 Ramp Length (cm) Ramp Height (cm) Ramp Angle (deg.) Trial 1 Time (s) Trial 2 Time (s) Trial 3 Time (s) Average Time (s)

POSTLAB:

1. Using Excel, create a spreadsheet and graph for this lab. Please note the formula for calculating angle: Angle = ASIN(h/l)*180/3.14159 NOTE: Will the computer understand h and l?

2. PRINT BOTH the spreadsheet and graph! (on one page, if possible)
3. Write a complete lab report for this lab. Use the assigned format and submit on __________. Include your Excel spreadsheet and graph as part of the lab report.

MINI-LAB: Determing acceleration
PART A: We will determine the acceleration of a

student who is speeding up. Our lucky volunteer is: _____________________.

This student began by walking ____________ in a time of ____________.
The student then sped up over a period of ____ seconds.
The student then took a time of________ to cover a distance of ___________.
1. Compute the initial velocity:

2. Compute the final velocity:

3. Compute the acceleration:
PART B: We will determine the acceleration of a

student who is slowing down. Our lucky volunteer is: _____________________.

This student began by running ____________ in a time of ____________.
The student then slowedd down over a period of ____ seconds, coming to a complete stop.
1. Compute the initial velocity:
2. State the final velocity, and explain:
3. Compute the acceleration:

ACCELERATION AND GRAPHING

1. Graph the following data:
time(s): 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10 11 12 13 14 15 16
speed (m/s): 22 22 22 26 30 34 38 42 42 42 35 27 15 7.0 2.0 0.0

2. During what period(s) of time was the car travelling at a constant speed?

3. During what period(s) of time was the car accelerating?
4. During what period(s) of time was the car decelerating?
5. When was the car accelerating smoothly (constantly)?

5B. Compute the acceleration during this period:

6. Compute the acceleration between the 14th and 15th seconds:

FRICTION WORKSHEET

1. DEFINE THE FOLLOWING TERMS:
Friction -

Normal force -

Coefficient of static friction ( ) -

Coefficient of kinetic (sliding) friction ( ) -

Drag -

2. What factors does the amount of friction depend on?

3. What are some of the effects of unwanted friction?

4. What can be done to reduce friction?

5. Briefly explain situations where friction is a desireable (good) thing and situations where it is undesireable (bad):

good:________________________________________________________________
good:________________________________________________________________
good:________________________________________________________________
6. Unbalanced forces cause _________________________.
7. The engine of a car is applying a constant force of 1200N (forward) to the car, yet the car continues to travel in a straight line at a constant speed of 55MPH. Explain, in several sentences, how this force is not causing the car to accelerate:

PHYSICAL SCIENCE PROBLEMS -- FRICTION

1. It takes a force of 14lbs to just begin sliding 2. It takes a force of 80N to keep a 200N wood box

a 28lb wooden crate on a leather conveyor belt. sliding on a leather belt. Compute the coefficient

Compute the coeff. of static friction for wood of sliding (kinetic) friction of leather on wood.

on leather:

3. Complete the table below with the values from above:

COEFFICIENT OF COEFFICIENT OF

STATIC FRICTION KINETIC FRICTION

WOOD ON WOOD .7 .4

STEEL ON STEEL .15 .09

WOOD ON LEATHER ____ ____

METAL ON RUBBER .65 .55

RUBBER ON DRY CONCRETE .9 .7

RUBBER ON WET CONCRETE .7 .57

4. What force would be needed to slide a 5. What force would be needed to start sliding

350N steel toolchest along a steel floor? a 2300lb car along a dry concrete road?

6. What force would be needed to slide a 70lb 7. What force would be needed to push a 400N

wooden chest along a wooden floor? steel filing cabinet along a rubber belt?

8. Making reference to the table above, explain why a person should slow down when driving on wet roads:

PHYSICAL SCIENCE PROBLEMS -- FRICTION
COEFFICIENT OF COEFFICIENT OF

STATIC FRICTION KINETIC FRICTION

WOOD ON WOOD .7 .4

STEEL ON STEEL .15 .09

WOOD ON LEATHER .5 .4

METAL ON RUBBER .65 .55

RUBBER ON DRY CONCRETE .9 .7

RUBBER ON WET CONCRETE .7 .57

1. It takes a force of 500N to just begin sliding a 2. It takes a force of 400N to keep the same crate

80kg wooden crate on a rubber conveyor belt. Sliding on the rubber belt. Compute the coeff. of sliding

Compute the coeff. of static friction for wood on (kinetic) friction of rubber on wood.

rubber:

3. What force would be needed to slide a 140kg 4. What force would be needed to start sliding a

couch (with steel legs) on a wooden floor? 25 000 lb truck on a wet concrete road?

5. What force would be needed to slide a 45 kg 6. What force would be needed to push a 800N

wooden chest along a wooden floor? steel fitness center along a metal floor?

7. Describe -- in detail -- 3 beneficial uses of friction in vehicles:

PHYSICAL SCIENCE -- FRICTION LAB
OBJECTIVES:

1. To observe the difference between sliding (kinetic) and static friction, and to measure both for a wooden block sliding on a table top.

2. To determine the effect of increased weight on sliding (kinetic) friction, and to determine the coefficient of kinetic friction for a wooden block sliding on a table top.

I. KINETIC (SLIDING) VERSUS STATIC FRICTION:

Place a wooden block on the table and attach a spring scale as demonstrated. Place a 1000g mass on the block.

trial number

1 2 3 AVE.

Force needed to JUST

start block sliding (fs): _______ _______ _______ _______

Force to keep block sliding

at a constant speed (fk): _______ _______ _______ _______

II. EFFECT OF NORMAL FORCE (WEIGHT) ON SLIDING FRICTION:

Measure the force needed to keep the block moving at a constant slow speed, as various masses are added to the block.

Mass of wooden block = ______

 MASS ADDED (g) TOTAL MASS “m” (g) WEIGHT “W” (N) FRICTION Trial 1 “f1” (N) FRICTION Trial 2 “f2” (N) FRICTION Trial 3 “f3” (N) AVERAGE FRICTION “fk” (N) COEFFIFIENT OF KINETIC FRICTION “μk” (N)

Complete a graph of W versus fk as part of the lab report.

THE FRICTION OF VARIOUS SURFACES
Complete the following table as instructed in class:

 SURFACE MATERIAL Kinetic friction (fk) Trial 1 (N) Kinetic friction (fk) Trial 2 (N) Kinetic friction (fk) Trial 3 (N) Average Kinetic friction (fk) (N)

Now, graph these data, using Excel.

THE FRICTION OF VARIOUS SURFACES
Complete the following table as instructed in class:

 SURFACE MATERIAL Kinetic friction (fk) Trial 1 (N) Kinetic friction (fk) Trial 2 (N) Kinetic friction (fk) Trial 3 (N) Average Kinetic friction (fk) (N)

Now, graph these data, using Excel.

PHYSICAL SCIENCE -- LAB ACTIVITY: USING PENDULUMS TO DETERMINE g
OBJECTIVES: 1. Explain factors that may affect a pendulum's period.

2. Using pendulums, calculate g.

1. DEFINE:

g -

period -

2. List factors that MIGHT affect the period of the demonstrated pendulum:

3. We will do a few demonstrations to test each of these, then complete:

The period of the pendulum does NOT depend on:___________________________
The period of the pendulum does NOT depend on:___________________________
The period of the pendulum DOES depend on:___________________________
4. Fill in the data table below with the data collected in class.

 LENGTH “l” (m) PERIOD “T” (s) ACCELERATION DUE TO GRAVITY (g) (m/s2)

5. Use the formula at right to calculate g = 2l

values for g and complete the data table. T2
6. Compute an average value for g: ______________
7. ESSAY: How does your value for g compare to the accepted value of 9.8 m/s2 ? Comment on possible sources of error in this experiment.

Newton's Second Law Problems.

1. Compute the force needed to accelerate a 30 kg dog at 3.0 m/s2.

2. Compute the acceleration that a 250 N force would give a 50 kg runner.

3. Find the mass of a truck if 8000 N causes an acceleration of 3.2 m/s2.

4. What force is needed to accelerate a 200g model rocket at 20 m/s2.

5. A 1500kg car slows from 30 m/s to 15 m/s in 5 seconds. Compute the car's acceleration.
6. What force were the brakes of the car in the previous problem exerting?
7. A 100 kg bike and rider was traveling at 3.0 m/s. The rider then applie`d a forward force of 50N for 4 seconds. What was the bike's final velocity?

NEWTON'S SECOND LAW

1.0 MPH = 1.6 km/hr = .45 m/s
1. You own and drive a car that, with you in it, weighs 2,200 lb (1000kg). The maxium force the brakes can apply is 10,000 N.
A. How long will it take you to come to a stop if you are traveling at 55MPH?
B. How far will you travel in this time, if the distance is given by:

d = 1/2at2 (NOTE: this formula only works if vf or vi =0)?

2. You pick up 5 friends who weigh a total of 770lb (350kg). Recalculate A. and B. from #1, ON A SEPARATE PAGE.

4. There is a curve near your house that you (alone) usually take at 40MPH. This change of direction requires the car to accelerate at 4.4m/s. Compute the force on your wheels.

5. The maximum force the wheels can withstand, w/o skidding, is 5,000N. Compute the force if you take the same curve at the same speed with your 5 friends (from #2).
6. Again, how should your driving change?

Momentum Problems

1. What force would be needed to accelerate a 7.0 kg block at 2.0 m/s2?
2. Find the momentum of a 400kg cow running at 8.0 m/s.
3. A bike and rider has 400 (kg*m)/s of momentum. Calculate the mass of the bike and rider if it is travelling at 3.4 m/s:

4. If a ship travels at 5.0 miles per hour, how long will it take to go 600 miles?

5. Find the momentum of a 8kg shotput traveling at 12.0 m/s.

6. A bike and rider has 500 (kg*m)/s of momentum. Calculate the speed of the bike and rider their combined mass is 50 kg.

7. Pick a sport or activity. Explain how to improve at this sport or activity, using TWO of the concepts from this "unit." Answer on the back of this page. At the top of the page, write the sport or activity you choose. Then EXPLAIN FULLY!!!!!

PROBLEMS -- SHOW ALL FORMULAS, WORK, ETC.
1. Label forces:
1A. The block weighs 80,000N. Determine the force needed to keep the block moving. uk = .3 us = .4

1B. What force would be needed to accelerate the block at 2.0 m/s2.

2. Find the momentum of a 400kg cow running at 8.0 m/s.

3. A force of 400N accelerates a bike at 3.0 m/s2. Calculate the mass of the bike:

4. Pick a sport or activity:___________________. Explain how to improve at this sport or activity, using TWO of the concepts from this "unit."

SCIENCE AND THE OLYMPICS NAME:_______________________________

EVENT:_______________________________
WRITE an essay of 100-200 words on the following topic:
As an athlete in the next Olympics, how will your Physical Science knowledge help you to win the gold? Specifically, discuss at least three of the areas shown below (in capital letters), and relate them to specific aspects of your event, performance, equipment, training, etc.

COMPOSITION OF MATTER ENERGY

phases of matter Conservation of

phase changes kinetic

elements, compounds potential

atoms, molecules various forms

physical properties changes from form to form

chemical properties heat

chemical changes entropy

LINEAR MOTION CIRCULAR AND ROTATIONAL MOTION

speed angular momentum

velocity centripetal force

acceleration centripetal acceleration

deceleration

mass

distance and time

force FORCE

momentum balanced forces

inertia acceleration

Newton's first law unbalanced forces

Newton's second law gravity

Newton's third law

WORK AND POWER WAVES

work sound

power transverse, longitudinal

simple machines wavelength

compound machines amplitude

forms, uses, etc.

OTHER

See me for approval

Momentum Problems
1. Define MOMENTUM:

2. State the Law of Conservation of Momentum:

3. A bowling ball (8.2 kg) is traveling at 4.0 m/s when it strikes a .50 kg pin.

A. Before collision, the ball's momentum is:

B. If the ball slows to 3.5 m/s because of the collision, how much momentum does it now have?

C. How much momentum did the ball lose?

D. How much momentum did the pin gain?

E. What is the pin's velocity?
4. A 20g bullet is fired from a 2.0 kg gun, which is lying on a frictionless surface. The bullet traveled at 500 m/s.
A. What was the momentum of bullet and gun (total) before the bullet was fired?

B. What is the momentum of the bullet, after being fired?

C. What is the gun's momentum?

D. What speed does the gun travel at?

Conservation of Momentum
1. A 70 kg knight is riding a 500 kg horse at 20 m/s.

A. Find the momentum of the horse and knight together (as one object):

B. If the horse could instantly stop (as it sometimes seems they can...), what would its new momentum be?

C. Where did all the momentum go? Assuming that the horse "gives" all of its momentum to the knight, what happens?

D. Find the new velocity of the knight:

E. What really happens?

2. An "unbraked" 300 kg catapult fires a stone (50kg) at 70m/s.

A. What happens to the catapult?

B. Just before the catapult is fired, what is the total momentum of the catapult and rock?

C. Determine the momentum of the rock that is fired:
D. Find the catapult's velocity just after it fires the rock:

PHYSICAL SCIENCE -- LAB ACTIVITY

USING PENDULUMS TO DETERMINE g
1. DEFINE:

g -

period -

2. Fill in the data table below with the data collected in class.

 OBJECT MASS (g) MASS (kg) PENDULUM LENGTH (m) PERIOD (s) ACCELERATION DUE TO GRAVITY (g) (m/s2)

3. Does the period of the pendulum depend on the mass? Explain.

4. Use the formula at right to calculate

values for g and complete the data table.

5. Compute an average value for g: ______________
6. ESSAY: How does your value for g compare to the accepted value of 9.8 m/s2? Comment on possible sources of error in this experiment: