physics chapter 3

While you're in a bus that moves at 100 km/h, you walk from the back to the front at 10 km/h. What is your speed relative to the road outside?

110 km/h

An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about

10 m/s.

If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by about

10 m/s.

If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about

1 second.

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

20 km/h.

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be

20 m/s.

A ball freely falling at 20 m/s will in the next second have a speed of _______.

30 m/s

Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration in meters per second per second?

4.0

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, one second later the rock's speed is

4.9 m/s.

In its first second of free fall, a dropped softball will fall a vertical distance of _______.

5 m

One half second after starting from rest, a freely falling object will have a speed of about

5 m/s.

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is

6 km/h/s.

If you drop an object, it will accelerate downward at a rate of 9.8 meters per second per second. If you instead throw it downwards, its acceleration (in the absence of air resistance) will be

9.8 meters per second per second.

Which best describes what occurs when a body accelerates?

Change in velocity per unit time

Calculate the acceleration of a car (in km/h⋅s) that can go from rest to 130 km/h in 10 s .

a = 13 km/h⋅s

A car takes 7.0 s to go from v=0m/s to v = 26 m/s at constant acceleration. If you wish to find the distance traveled using the equation d=1/2at^2, what value should you use for a?

a = 3.7 ms^2

Calculate the acceleration of a ball that starts from rest, rolls down a ramp, and gains a speed of 30 m/s in 5.6 seconds.

a = 5.4 ms^2

Galileo discovered that when air resistance can be neglected, all objects fall with the same _______.

acceleration

When we're talking about how quickly "how fast" changes, we're talking about _______.

acceleration

The difference between speed and velocity involves _______.

direction

A bullet is dropped from the top of the Empire State Building while another bullet is fired downward from the same location. Neglecting air resistance, the acceleration of...

each bullet is 9.8 meters per second per second.

In each second of fall, the distance a freely falling object will fall is

increasing.

A speedometer normally measures _______.

instantaneous speed

A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet in meters per second per second

is 9.8.

A ball is thrown upwards and caught when it comes back down. In the presence of air resistance, the speed with which it is caught is always

less than the speed it had when thrown upwards.

Twelve seconds after starting from rest, an object falling freely will have a speed of

more than 100 m/s.

While a car travels around a circular track at a constant speed, its... velocity is zero. inertia is zero. acceleration is zero. none of the above

none of the above

An apple drops from a tree and hits the ground in 1.5 s. Calculate how far it falls. Distance fallen in free fall, from rest: d=1/2gt^2

s = 11 m

Calculate the distance you will travel if you maintain an average speed of 11 m/s for 34 seconds. Distance = average speed × time

s = 370 m

Each second, a ball rolling down an inclined plane picks up _______.

the same amount of speed

Drop a rock from a 5-m height and it accelerates at 10 m/s2 and strikes the ground 1 s later. Drop the same rock from a height of 2.5 m and its acceleration of fall is about

the same amount.

Galileo's definition of speed was a breakthrough because he is acknowledged to be the first to consider _______.

time

Calculate the instantaneous speed (in m/s) at the 13-second mark for a car that accelerates at 3.0 m/s2 from a position of rest. Instantaneous speed = acceleration × time

v = 39 m/s

Calculate your average speed if you run 58 meters in 8.0 seconds. Average speed =total distance covered/time interval

v ave = 7.3 m/s

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds?

about 50 m/s

Calculate the average speed (in km/h) of Larry, who runs to the store 4.0 kilometers away in 32 minutes.

v ave = 7.5 km/h

While an object near the Earth's surface is in free fall, its

velocity increases.

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

zero.