WTMA Force, Motion, and Friction 5 — Questions and Answers
Question 1: A 200 N force is applied at an angle of 60° above horizontal to push a box across the floor. What is the horizontal component of this force?
- 100 N (Correct answer)
- 173 N
- 200 N
- 50 N
Correct answer: 100 N
The horizontal component is F × cos(60°) = 200 × 0.5 = 100 N.
Question 2: Which situation has the LEAST friction?
- A steel ball bearing rolling in a steel race (Correct answer)
- A rubber stopper dragged across asphalt
- A wooden block slid across rough concrete
- A brick dragged across a brick surface
Correct answer: A steel ball bearing rolling in a steel race
Ball bearings are specifically designed to minimize friction through rolling contact and smooth, hardened steel surfaces.
Question 3: A machine part moves in a circle at constant speed. Which statement is true?
- Its speed is constant but its velocity is changing (Correct answer)
- Both speed and velocity are constant
- Its velocity is constant but its speed changes
- Neither speed nor velocity changes
Correct answer: Its speed is constant but its velocity is changing
Circular motion at constant speed still involves changing velocity because velocity is a vector and the direction continuously changes.
Question 4: A pulley system is used to lift a 300 N load with only 150 N of effort. What is the mechanical advantage?
- 2 (Correct answer)
- 0.5
- 150
- 300
Correct answer: 2
Mechanical advantage equals load force divided by effort force: 300 N ÷ 150 N = 2.
Question 5: A gear with 40 teeth meshes with a gear with 10 teeth. If the small gear turns at 200 RPM, how fast does the large gear turn?
- 50 RPM (Correct answer)
- 800 RPM
- 200 RPM
- 400 RPM
Correct answer: 50 RPM
Gear ratio = 40/10 = 4, so the large gear turns at 200 ÷ 4 = 50 RPM.
Question 6: A crate sits on a flatbed truck. The truck accelerates forward. In which direction does friction on the crate act?
- Forward, in the direction of truck acceleration (Correct answer)
- Backward, opposing truck motion
- Downward, into the truck bed
- No friction acts since the crate isn't sliding
Correct answer: Forward, in the direction of truck acceleration
Static friction acts forward on the crate to accelerate it along with the truck, preventing the crate from sliding backward.
Question 7: Two identical blocks are connected by a rope and pulled across a frictionless surface by a 20 N force. What is the tension in the rope between the blocks?
- 10 N (Correct answer)
- 20 N
- 40 N
- 5 N
Correct answer: 10 N
The rope must accelerate only one block (half the total mass), so tension is half the applied force: 20 N ÷ 2 = 10 N.
WTMA Force, Motion, and Friction 5
A 200 N force is applied at an angle of 60° above horizontal to push a box across the floor.
What is the horizontal component of this force?