Bennett Mechanical Test Bennett Mechanical Friction and Inclined Planes Questions and Answers 2 ā Questions and Answers
Question 1: If the angle of an inclined plane increases, what happens to the force needed to push an object up it?
- It decreases
- It remains the same
- It increases (Correct answer)
- It depends only on mass
Correct answer: It increases
A steeper angle increases the parallel gravity component, so more force is needed to push the object upward.
Question 2: A wedge is a type of simple machine based on which underlying principle?
- Pulley
- Lever
- Inclined plane (Correct answer)
- Wheel and axle
Correct answer: Inclined plane
A wedge is essentially two inclined planes joined back-to-back, using the same mechanical advantage principle.
Question 3: Which factor does NOT affect the magnitude of the kinetic friction force between two surfaces?
- Normal force
- Area of contact (Correct answer)
- Coefficient of kinetic friction
- Surface material
Correct answer: Area of contact
For most surfaces, friction force depends on normal force and the coefficient of friction, not on contact area.
Question 4: A 50 kg crate rests on a 30Ā° incline (g = 10 m/sĀ²). What is the normal force the incline exerts on the crate?
- 500 N
- 250 N
- 433 N (Correct answer)
- 288 N
Correct answer: 433 N
Normal force = mg cos30Ā° = 500 Ć 0.866 ā 433 N.
Question 5: Static friction compared to kinetic friction for the same pair of surfaces is always:
- Less than kinetic friction
- Equal to kinetic friction
- Greater than or equal to kinetic friction (Correct answer)
- Exactly twice kinetic friction
Correct answer: Greater than or equal to kinetic friction
It takes more force to start an object moving than to keep it moving, so static friction ā„ kinetic friction.
Question 6: A screw is best described as which simple machine wrapped around a cylinder?
- Lever
- Pulley
- Inclined plane (Correct answer)
- Wedge
Correct answer: Inclined plane
A screw thread is a continuous inclined plane helically wrapped around a cylindrical shaft.
Bennett Mechanical Test Bennett Mechanical Friction and Inclined Planes Questions and Answers 2
If the angle of an inclined plane increases, what happens to the force needed to push an object up it?