Bennett Mechanical Test Velocity and Gravity 4

Question 1

A train decelerates from 30 m/s to 0 m/s in 10 seconds. What is its acceleration?

Accepted Answer

-3 m/s²

Answer

Acceleration is (0−30)/10 = −3 m/s², negative because it slows down.

Question 2

Terminal velocity occurs when which forces are balanced?

Accepted Answer

Gravity and air resistance

Answer

At terminal velocity the upward air resistance equals the downward gravity, so speed stays constant.

Question 3

Which object would reach terminal velocity sooner when falling?

Accepted Answer

A large open parachute

Answer

The parachute's large surface creates more air resistance, balancing gravity at a lower speed sooner.

Question 4

A ball thrown upward at 20 m/s takes about how long to reach its highest point?

Accepted Answer

2 seconds

Answer

Time equals velocity divided by g, 20 ÷ 10 = 2 seconds.

Question 5

If you double an object's speed, how does its velocity vector change in magnitude?

Accepted Answer

It doubles

Answer

The magnitude of velocity is the speed, so doubling speed doubles the velocity magnitude.

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