Simple Machines – Q&A Practice
Q1. How does a movable pulley function?
A movable pulley reduces the effort needed to lift a load by increasing the distance through which the effort is applied. Its mechanical advantage is 2.
Q2. Mathews used a lever to move a box that weighed 400 N. If the effort arm was 72 cm and load arm 12 cm, calculate the mechanical advantage of the lever and the effort required to overcome the load.
Mechanical Advantage (MA) = Effort arm / Load arm = 72/12 = 6.
Effort = Load / MA = 400 / 6 ≈ 66.7 N.
Q3. Define a simple machine. List three ways it can reduce our work.
A simple machine is a device that makes work easier by multiplying force, changing its direction, or increasing speed.
It reduces work by: 1. Multiplying force. 2. Changing the direction of force. 3. Increasing speed of motion.
It reduces work by: 1. Multiplying force. 2. Changing the direction of force. 3. Increasing speed of motion.
Q4. State two functions of a wheel and axle.
1. It multiplies force to lift or move loads.
2. It helps in reducing friction and makes transport easier (e.g., carts, vehicles).
2. It helps in reducing friction and makes transport easier (e.g., carts, vehicles).
Q5. Explain the following -MA>1,MA=1 and MA<1
MA > 1: The machine multiplies effort, so a small effort can lift a large load.
MA = 1: The machine does not multiply effort but only changes its direction.
MA < 1: The machine requires more effort than load but provides a gain in speed or distance.
Q6. What is the role of wear and tear in increasing the efficiency of simple machines?
Wear and tear reduce efficiency because energy is wasted in overcoming friction. Reducing wear and tear increases the efficiency of machines.
Q7. Does an inclined plane increase work? Explain.
An inclined plane does not reduce the total work done. It only reduces the effort required by increasing the distance over which the load is moved.
