physics chapter three

A ball traveling at 3 m/s East hits a wall and bounces off heading West traveling at 2 m/s. If the change in direction took 0.4 second, what is the average acceleration of the ball?

12.5 m/s2 West.

Suppose you drove 120 miles due east in 3 hours, turned around and drove 60 miles due west in 1 hour. Assuming due east is the positive direction, what is your average velocity for the entire trip?

15

Assume the position of a kite is given by the function s(t) where t is in seconds. Suppose the average velocity of the kite between t = 1 and t = 5 is 22 meters per second. If the kite at time t = 5 is at a position of 90 meters (i.e. s(5) = 90), what is the position of the kite at time t = 1?

2

Your friend walks 15 minutes from her house to the school every day. What is her walking speed, if her house is 0.5 miles from her school?

2 mph

Using this graph, how long did it take for the object to move its first 10 meters?

2 seconds

Consider a man walking around a house in a rectangle pattern. He walks 70 feet across the front, 30 feet along the side, 70 feet along the back, and 30 feet along the other side to bring him back to where he began. How much distance did this man cover?

200 feet

What is the change in velocity of the object between 4 and 7 seconds?

21 m/s

A cheetah running at a velocity of 18 m/s accelerates 1 m/s2 for 5 sec. What is the final velocity of the cheetah?

23 m/s

Using this graph, what is the distance of the object from the start point at 15 seconds?

25 m

A marathon runner runs with an average velocity of 5.5 m/s. How long in seconds does it take for the runner to travel 158 m? (Round to the nearest second.)

29 s

For this graph, calculate the average speed between 12 seconds and 20 seconds.

3.8 m/s

On this graph, what is the change in velocity between 5 seconds and 8 seconds?

30 m/s - 5 m/s = 25 m/s

A car driving on a straight track accelerates at a rate of 3.2 m/s^2 for 14 sec. If the initial velocity of the car was 5.1 m/s, and its initial position was 0 m, what is its final position?

385 m

You drive from your house to the dry cleaners, which is 12 miles east of your house. You then drive to the grocery store from the dry cleaners. The grocery store is 15 miles west of your house. What distance did you cover?

39 miles

For this graph, calculate the total average speed.

4.5 m/s

Which is an accurate velocity reading?

40 miles per hour south

If a ball is dropped from a 100 m cliff, it accelerates at a constant rate of 9.8 m/s2. Assuming its initial velocity is 0 m/s, its initial position is 0 m and its final position is 100 m away from the initial position, what is the velocity of the ball when it hits the ground?

44.3 m/s.

Calculate the slope of the line on the graph.

5

Solve: A car is traveling east, and travels 200 miles in 4 hours. What is the instantaneous velocity (assuming the car is traveling the same speed the entire time) in miles per hour 75% of the way through the trip?

50 miles per hour east

What is the acceleration of the object between 4 and 7 seconds?

7 m/s2

Using this graph, at what point is there a change in direction?

7 seconds

An 80-lb cheetah jogging left at 15 m/s suddenly accelerates to 30 m/s. The cheetah crosses about 45 meters of savannah and needs 2 seconds to reach 30 m/s. What was the cheetah's acceleration?

7.5 m/s^2 left

Solve: A car is going north and travels 60 miles in 50 minutes. What is the instantaneous velocity (assuming the car is traveling the same speed the entire time) in miles per hour halfway through the trip?

72 miles per hour north

A fighter jet accelerates at an average rate of 10.43 m/s2 and takes 6.9 sec to take off. If the jet takes off after 250 m, what was its final takeoff velocity?

72.2 m/s

Which of the following is a vector quantity?

8 meters/second west

Which of the following objects is accelerating?

A car driving around a circular track with a constant speed of 100 km/h

Displacement is defined by which one of the following?

The difference between the final position and the initial position of a path taken by an object

You and your dog take a walk from your house to the park. As you walk to the park, your dog runs around and chases squirrels and investigates fire hydrants while you just walk directly to the park. Whose displacement is larger, you or your dog?

The displacement for both of us is the same.

On a velocity vs. time graph, a line that crosses the x axis represents

The object is changing direction

What does a diagonal upwards-sloping line on a position-time graph mean?

The position is changing -- the object is moving away from the origin.

Which of the following is the best definition of velocity?

The rate of change in displacement with respect to time

For which of these aspects of kinematics do you need to use time as a factor?

The speed of an object

In Latin, the suffix -ics means

The study of

The term kinematics refers to

The study of motion

Consider a man walking around a house in a rectangle pattern. He walks 70 feet across the front, 30 feet along the side, 70 feet along the back, and 30 feet along the other side to bring him back to where he began. What is the displacement of the man walking around the house?

There was no displacement as the man ended where he began

Which of these words accurately describes 'position'?

Vector

Kinematics can answer all of the following questions EXCEPT

Why does a baseball drop to the ground down after being thrown?

A car drives by at a speed of 8 m/s. Three seconds after the car passes you (t = 3 s) the driver hits the gas and the car begins to accelerate. Nine seconds after the car passes you (t = 9 s) the car has reached a speed of 40 m/s. What was the car's acceleration between t = 3 seconds and t = 9 seconds?

a = 32 m/s / 6 s = 5.3 m/s

On this graph, what is the acceleration between 10 seconds and 14 seconds?

a = Δv / Δ t = (10 m/s - 30 m/s) / (14 s - 10 s) = (-20 m/s) / (4 s) = -5 m/s^2

When driving over mountains, the grade of the road tells drivers how steep the climb is going up or down the mountain. The grade is the rate of change of _____.

elevation as a function of distance

Velocity is a rate of change of _____.

position as a function of time

Acceleration is the measure of how velocity changes over time. Acceleration is an example of _____.

rate of change.

A velocity must always include _____.

speed and direction

Acceleration can be defined as _____.

the rate of change of an object's velocity

You run around traveling a total of 45 meters and end up 1 meter to the right of the origin. The x-axis points left to right. The y-axis points up and down. What is your position?

+1 meter (x-direction)

What is the instantaneous velocity of the object at 2 seconds?

-0.5 m/s

For this graph, calculate the average velocity between 0 seconds and 3 seconds.

-5 m/s

Suppose you drove 120 miles due east in 3 hours, turned around and drove 180 miles due west in 5 hours. Assuming due east is the positive direction, what is your average velocity for the entire trip?

-7.5

Suppose the height of a bird in the sky, in feet, is given by the position function s(t) = 560 - 8*t, where t is in seconds. Determine the average velocity of the bird between t = 3 and t = 20 seconds.

-8

On this graph, what is the acceleration between 5 seconds and 8 seconds?

-8.3 m/s^2

Suppose the height of a ball, in meters, is given by the position function s(t) = -t^2 + 4*t, where t is in seconds. What is the average velocity of the ball between t = 1 second and t = 3 seconds?

0

For this graph, calculate the total average velocity.

0 m/s

On this graph, what is the acceleration between 1 seconds and 5 seconds?

0 m/s^2

You drive from your house to the dry cleaners, which is 12 miles east of your house. You then drive to the grocery store from the dry cleaners. The grocery store is 15 miles west of your house. You then drive back home from the grocery store. What was your displacement?

0 miles

What is the average acceleration of an object that is moving at 5 m/s, and 3 seconds later is traveling at 10 m/s?

1.67 m/s2

Using this graph, at what time is the object not moving?

10 seconds

Consider a man walking around a house in a rectangle pattern. He walks 70 feet across the front, 30 feet along the side, 70 feet along the back, and 30 feet along the other side to bring him back to where he began. If it took the man 2 minutes to complete the walk, what was his speed?

100 feet/minute

On a position vs. time graph, with position on the y-axis and time on the x-axis, a change in direction is represented by

A line that is initially moving upwards, then turns downward

What is position in physics?

A place where someone or something is located in terms of an axis.

This graph is broken up into 5 sections, labeled A-E. On this graph, what section(s) represents positive acceleration?

A, B, D

This graph is broken up into 5 sections, labeled A-E. On this graph, what section(s) represents no acceleration?

C

Average acceleration is determined by which of the following?

Change in velocity / change in time

The difference between velocity and speed is that velocity also includes the _____ an object is traveling.

Direction

This graph is broken up into 5 sections, labeled A-E .On this graph, what section(s) represents negative acceleration?

E

When you blow up a balloon, the time that it takes to blow it up depends on how much pressure the inlet air is under. (AKA, how hard you blow!) If the pressure is higher, the rate of change of the balloon volume _____ as a function of time.

Increases

Which term refers to a data reading that is taken at a particular moment in time?

Instantaneous

Velocity is a vector quantity meaning all answers must include

Magnitude, direction, and units

In Greek, Kinemat- means

Motion

You and your dog take a walk from your house to the park. As you walk to the park, your dog runs around and chases squirrels and investigates fire hydrants, while you just walk directly to the park. Who covered more distance, you or your dog?

My dog