Chapter 4 Linear Motion

Suppose you take a trip that covers 240 km and takes 4 hours. Your average speed is

60 km/h

T or F A ball is thrown into the air at the highest point the ball has zero velocity and acceleration

false

T or F A ball is thrown into the air. At the highest point, the ball has zero velocity and zero acceleration.

false

T or F A unit of velocity is meter

false

T or F As a ball falls freely, the distance it falls each second is the same

false

T or F As the ball falls freely the distance it falls each second is the same

false

a ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always

directed downward

T or F Average speed is defined as the time it takes for a trip divided by the distance

false

T or F Unless said otherwise when we discuss the speed of things we mean with the respect of the center of the universe

false

T or F When a car rounds a corner at a constant speed its acceleration is 0

false

T or F When a car rounds a corner at a constant speed, its acceleration is zero.

false

T or F The SI unit of acceleration is meters per second.

false // meters per second SQUARED

When you look at the speedometer in a moving car, you can see the car's

instantaneous speed

The hang time (time once feet are off the ground in a jump) for most athletes is

less than one second

One possible unit of speed is

miles per hour, light years per century, kilometers per hour, all of the above

acceleration is defined as

the rate at which velocity itself changes

T or F Even though a car is slowing down it is still accelerating in the most general definition of acceleration

true

T or F The rate at which distance is covered is called speed

true

T or F The rate at which velocity changes with time is acceleration

true

T or F The rate at which velocity changes with time is called acceleration.

true

Acceleration is defined as the CHANGE in

velocity divided by the time interval

As an object falls freely in a vacuum, its

velocity increases

Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour. Which of the following is NOT true?

your velocity is constant

The vertical attained by a basketball player who achieves a hang time of a full one second is about

1.2 meters

A stone is dropped from a cliff. After it has fallen 10 m, what is the stone's velocity?

14 m/s

What is the average speed of a cheetah that runs 88 meters in 5 seconds?

17.6 meters per second

What speed must you toss a ball straight up that it takes four seconds to return to you?

20 m/s

What is the average speed of a cheetah that runs 70 m in 2.5 seconds?

28 m/s

A skateboarder starting from rest accelerates down a ramp at 2 m/s^2 for 2 s. What is the final speed of the skateboarder?

4 m/s

Suppose a car is moving in a straight line and steadily increases its speed. It moves from 35 km/h to 40 km/h the first second and from 40 km/h to 45 km/h the next second. What is the car's acceleration?

5 km / h / s

a pencil lies on your desk if the earth is moving around the sun at around 30 km/s. How fast is the pencil moving relative to the desk? How fast is the pencil moving relative to the sun?

0 km/s , 30 km/s

You toss a ball at 5 ms straight upwards how much time would it take for the ball to reach the top of its path.

0.5 s

Suppose a car is moving in a straight line and steadily increases it speed from 35 km to 40 km per hour the first second to 40 to 45 km What is the cars acceleration?

5 km/h /s

Write a short paragraph explaining what acceleration is and why a car is accelerating as it rounds a corner

acceleration is a change in velocity, which has both a magnitude and a direction. so if you round a corner at a constant speed, the direction in which you are traveling is changing, so therefore the velocity is changing, and there is an acceleration present. of course, if you round a corner at a non-constant speed, it's obvious that there will be an acceleration as well.

An apple falls from a tree and one-half second later hits the ground. How fast is it falling when it hits the ground?

V = g t = 9.8 m/s² 0.5 s, || v = 4.9 m/s

Speed is

a measure of how fast something is moving, always measure in terms of a unit of distance divided by a unit of time, the distance covered per unit time // ALL OF THE ABOVE

A ball is thrown straight up. At the top of its path its acceleration is

about 10 m/s2

T or F A unit of acceleration is meters per second

False