Author Question: The speedometer of a car indicates a constant speed of 30 miles per hour. From this we can say that ... (Read 78 times)

charchew · **on:** Jul 29, 2018

The speedometer of a car indicates a constant speed of 30 miles per hour. From this we can say that the acceleration of the car is

1) zero.
2) nonzero.
3) can't really say.

This is because
4) no net force is acting on the car.
5) any reading (other than zero) on the speedometer indicates acceleration.
6) the car may be changing its direction.

Question 2

If an object is thrown downward from a tall cliff, its acceleration while falling (in the absence of air resistance) will be

1) less than 10 m/s2.
2) 10 m/s2.
3) greater than 10 m/s2.

This is evident from the fact that
4) gravitational force depends upon the state of motion of an object.
5) each successive second the speed of the object increases by an additional 10 m/s.
6) the object was not simply dropped but thrown, therefore having an initial acceleration of fall greater than zero.