Which simple machine is a rigid bar that pivots around a point to move an object?

• Lever

• Pulley

• Screw

• Inclined Plane

Answer explanation

A lever is a simple machine consisting of a rigid bar that pivots around a fixed point called the fulcrum. It is used to lift or move objects by applying force at one end, making it the correct answer.

The primary function of a wedge is (a)  

• To push materials apart and cut things
• To hold things together

• To measure distances

• To create sound.

Answer explanation

The primary function of a wedge is to push materials apart and cut through them. Wedges are designed to convert force applied to their blunt end into a splitting force, making them effective for cutting and separating objects.

What is the primary function of a wheel and axle?

• To increase friction

• To make it easy to move things by rolling them and reducing friction

• To make things heavier

• To stop movement

Answer explanation

The primary function of a wheel and axle is to facilitate movement by allowing objects to roll, which significantly reduces friction compared to dragging. This makes it easier to move heavy items.

Which of the following items is not an example of a screw?

• Jar lid

• Car jack

• Spinning stool

• Pulley

Answer explanation

A pulley is a simple machine used to lift objects, while a screw is a type of fastener. The jar lid, car jack, and spinning stool all involve screw mechanisms, making 'pulley' the correct answer as it is not an example of a screw.

What is required for a screw to move a short distance?

• Many twists

• A single push

• A long pull

• A quick slide

Answer explanation

A screw requires many twists to move a short distance because it converts rotational motion into linear motion. Each twist advances the screw slightly, making it the correct choice for this question.

How does a simple machine like stairs provide mechanical advantage?

• By making the task harder

• By making the task easier but taking longer

• By making the task impossible

• By making the task faster

Answer explanation

Stairs provide mechanical advantage by allowing a person to ascend with less effort compared to climbing straight up. While it may take longer to reach the top, the effort required is reduced, making the task easier.

What simple machines are combined in a wheelbarrow?

• Lever and pulley

• Wedge and screw

• Wheel and axle with a lever

• Inclined plane and wedge

Answer explanation

A wheelbarrow combines a wheel and axle for movement and a lever for lifting the load. The wheel and axle allow for easy transport, while the lever helps to lift and balance the weight, making this the correct choice.

Which of the following is an example of a complex machine? A) Hammer B) Car jack C) Screwdriver D) Nail.

• Hammer

• Car jack

• Screwdriver

• Nail

Answer explanation

A car jack is a complex machine because it consists of multiple parts working together to lift heavy objects, unlike a hammer, screwdriver, or nail, which are simple tools with single functions.

What is the main purpose of a wheel and axle?

• To increase speed

• To lift objects

• To reduce friction

• To cut materials.

Answer explanation

The main purpose of a wheel and axle is to reduce friction, making it easier to move objects. This mechanical advantage allows for smoother motion and less effort required to lift or transport items.

The pulley shown above is used to change the —

• amount of work done lifting

• direction of the applied force

• weight of the object to be lifted

• mechanical advantage of the rope

Answer explanation

The pulley changes the direction of the applied force, allowing you to lift an object by pulling down instead of lifting up. This makes it easier to lift heavy loads.