Physics Mechanics 5

Question 1

A rigid rod is pivoted at one end. A force of 20 N is applied perpendicular to the rod at a distance of 1.5 m from the pivot. What is the torque produced?

Accepted Answer

30 N·m

Answer

13.3 N·m

Answer

21.5 N·m

Answer

300 N·m

Question 2

A 3 kg object falls freely from rest. What is its speed after falling 20 m? (g = 9.8 m/s²)

Accepted Answer

19.8 m/s

Answer

9.9 m/s

Answer

14 m/s

Answer

196 m/s

Question 3

What is the impulse delivered to a 0.5 kg ball that changes its velocity from 4 m/s to −2 m/s (opposite direction)?

Accepted Answer

−3 N·s

Answer

3 N·s

Answer

−1 N·s

Answer

1 N·s

Question 4

Power is defined as the rate of doing work. Which formula correctly expresses power in terms of force and velocity?

Accepted Answer

P = F·v

Answer

P = F/v

Answer

P = F·v²

Answer

P = F/v²

Question 5

A 0.2 kg ball on a string of length 0.5 m moves in a vertical circle. At the top of the circle, what is the minimum speed needed so the string remains taut?

Accepted Answer

2.21 m/s

Answer

4.9 m/s

Answer

9.8 m/s

Answer

1.57 m/s

Question 6

A 60 kg skater moving at 4 m/s grabs a stationary 40 kg skater. What is their combined speed after?

Accepted Answer

2.4 m/s

Answer

4 m/s

Answer

1.6 m/s

Answer

6 m/s

Question 7

An object undergoes uniform circular motion. Which of the following is TRUE about its velocity and acceleration?

Accepted Answer

Velocity is constant in magnitude; acceleration points toward the center

Answer

Both velocity and acceleration are constant in magnitude and direction

Answer

Both velocity and acceleration point toward the center

Answer

Velocity and acceleration are always parallel