SIFT Physics and Simple Machines 5

Question 1

A lever has an effort arm of 3 m and a load arm of 0.5 m. What is its mechanical advantage?

Accepted Answer

6

Answer

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?

Accepted Answer

Wheelbarrow

Answer

In a wheelbarrow, the wheel (fulcrum) is at one end, the load is in the middle, and effort is at the other end — a second-class lever.

Question 3

Velocity differs from speed in that velocity also specifies:

Accepted Answer

Direction

Answer

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/s²)

Accepted Answer

150 J

Answer

PE = mgh = 5 kg × 10 m/s² × 3 m = 150 J.

Question 5

The mechanical advantage of a fixed pulley is:

Accepted Answer

1

Answer

A fixed pulley only changes the direction of the applied force; it does not multiply force, so its MA = 1.

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