chapter3 Flashcards
As you read this in your chair, how fast are you moving relative to the chair? Relative to the Sun?
You are not moving relative to the chair, but you are moving over 100,000 km/h relative to the Sun.
What is the average speed in kilometers per hour of a horse that gallops a distance of 15 km in a time of 30 min?
30 km/h
If a car is moving at 90 km/h and it rounds a corner, also at 90 km/h, does it maintain a constant speed? A constant velocity?
It maintains a constant speed, but does not maintain a constant velocity
Which BEST describes what occurs when a body accelerates?
Change in velocity per unit time
A ball rolling down an inclined plane each second picks up ______.
the same amount of speed each second
Galileo discovered that when air resistance can be neglected, all objects fall with the same ______.
acceleration
What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s?
10 km/h·s
What is the gain in speed per second for a freely falling object?
It gains approximately 10 m/s.
What exactly is meant by a “freely falling” object?
An object in free fall falls under gravity alone with no friction
What is the effect of air resistance on the acceleration of falling objects?
Air resistance decreases the acceleration of falling objects
What is the speed over the ground of an airplane flying at 100 km/h relative to the air caught in a 100-km/h right-angle crosswind?
141 km/h
Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the opposite direction. Jake’s speed relative to the ground is
6 m/s
When you walk at an average speed of 4 m/s, in 5 s you’ll cover a distance of
20 m
A vehicle undergoes acceleration when it
- gains speed.
- loses speed.
- changes its direction
While a car travels around a circular track at a constant speed, its
none
If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is
6 m/s2
An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration is
0
A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is
1 m/s2
If an object moves with constant acceleration, its velocity must
change by the same amount each second.
change by the same amount each second.
the same
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.
A car’s speed 3 seconds after accelerating from rest at 2 m/s2 is
6 m/s