Physics Mechanics 3

Question 1

A 2 kg object moving at 6 m/s has its velocity reduced to 2 m/s by friction. How much kinetic energy was lost?

Accepted Answer

32 J

Answer

16 J

Answer

4 J

Answer

36 J

Question 2

According to Newton's Third Law, when a horse pulls a cart forward, the cart pulls the horse:

Accepted Answer

Backward with an equal and opposite force

Answer

Forward with a smaller force

Answer

Backward with a smaller force

Answer

Not at all

Question 3

A spring with a spring constant of 200 N/m is compressed by 0.1 m. How much elastic potential energy is stored?

Accepted Answer

1 J

Answer

2 J

Answer

20 J

Answer

0.1 J

Question 4

Which condition must be true for an object to be in static equilibrium?

Accepted Answer

Net force is zero and net torque is zero

Answer

Net force is zero only

Answer

Net torque is zero only

Answer

The object must be at rest and have no acceleration

Question 5

An elevator accelerates upward at 2 m/s². What does a 70 kg person feel as their apparent weight? (g = 9.8 m/s²)

Accepted Answer

826 N

Answer

686 N

Answer

140 N

Answer

546 N

Question 6

A wheel rotating at 120 rpm is brought to rest in 4 seconds. What is its angular deceleration in rad/s²?

Accepted Answer

π rad/s²

Answer

30π rad/s²

Answer

2π rad/s²

Answer

60 rad/s²

Question 7

Which of the following correctly describes the center of mass of a system of particles?

Accepted Answer

The average position of mass weighted by each particle's mass

Answer

The point where all mass is physically concentrated

Answer

The geometric center of the object

Answer

The point of maximum density