SIFT Physics and Simple Machines 5 ā Questions and Answers
Question 1: A lever has an effort arm of 3 m and a load arm of 0.5 m. What is its mechanical advantage?
- 6 (Correct answer)
- 0.17
- 1.5
- 3.5
Correct answer: 6
MA = effort arm / load arm = 3 m / 0.5 m = 6, meaning the lever multiplies the effort force by 6.
Question 2: Which of the following is an example of a second-class lever?
- Wheelbarrow (Correct answer)
- Scissors
- Tweezers
- Seesaw
Correct answer: Wheelbarrow
In a wheelbarrow, the wheel (fulcrum) is at one end, the load is in the middle, and effort is at the other end ā a second-class lever.
Question 3: Velocity differs from speed in that velocity also specifies:
- Direction (Correct answer)
- Magnitude
- Acceleration
- Mass
Correct answer: Direction
Velocity is a vector quantity that includes both magnitude (speed) and direction, while speed is a scalar with magnitude only.
Question 4: A 5 kg object is lifted 3 meters. How much gravitational potential energy does it gain? (g = 10 m/sĀ²)
- 150 J (Correct answer)
- 15 J
- 1500 J
- 50 J
Correct answer: 150 J
PE = mgh = 5 kg Ć 10 m/sĀ² Ć 3 m = 150 J.
Question 5: The mechanical advantage of a fixed pulley is:
- 1 (Correct answer)
- 2
- 0.5
- Depends on the load
Correct answer: 1
A fixed pulley only changes the direction of the applied force; it does not multiply force, so its MA = 1.
Question 6: If you double the mass of an object while keeping acceleration constant, the required force:
- Doubles (Correct answer)
- Halves
- Remains the same
- Quadruples
Correct answer: Doubles
From F = ma, doubling mass while holding acceleration constant requires doubling the force.
Question 7: An inclined plane has a height of 2 m and a length of 8 m. What is its mechanical advantage?
- 4 (Correct answer)
- 0.25
- 16
- 6
Correct answer: 4
MA of an inclined plane = length / height = 8 m / 2 m = 4, meaning it takes one-fourth the force to push something up the ramp versus lifting it straight up.
SIFT Physics and Simple Machines 5
A lever has an effort arm of 3 m and a load arm of 0.5 m.
What is its mechanical advantage?