Force And Energy - Simple Machine Extra Questions And Answers - Class 5 Science - Complete Learning Material PDF

Ques 1: What is force?
Ans: A force is a push or a pull acting on an object. A force can make a still object start moving, make a moving object stop or change its direction, or change the shape of an object. For example, pushing a door to open it is a force.

Ques 2: What is gravity?
Ans: Gravity is the force that attracts objects towards the centre of the Earth. It gives objects weight and causes them to fall to the ground when released.

Ques 3: What is magnetism?
Ans: Magnetism is the force exerted by magnets. Magnets can attract or repel other magnets and can attract some metals such as iron and nickel. For example, a magnet pulls small iron pins towards it.

Ques 4: What is energy? Name any four types of energy.
Ans: Energy is the ability to do work. Four common types of energy are: heat energy (keeps us warm), light energy (helps us see), wind energy (moving air used to turn windmills), and sound energy (produced by vibrating objects).

Ques 5: What is a machine?
Ans: A machine is a tool that makes our work easier by changing the size or direction of a force. It helps us do tasks that would be difficult to do with our hands alone.

Ques 6: Name the six types of simple machines.
Ans: The six types of simple machines are:

1. Lever
2. Pulley
3. Wheel and axle
4. Wedge
5. Screw
6. Inclined plane

Ques 7: List the four effects that force has on objects.
Ans: The four effects that force can have on objects are:

1. A force can make a stationary object start to move or make a moving object move faster.
2. A force can make a moving object stop or slow it down.
3. A force can change the direction in which an object is moving.
4. A force can change the shape of an object.

Ques 8: What is friction? Why is friction necessary?
Ans: Friction is the force that opposes the sliding movement of one surface over another. Friction is necessary because it prevents us from slipping - for example, the friction between our feet and the ground makes it possible for us to walk.

Ques 9: List any two advantages and two disadvantages of friction.
Ans: The two advantages of friction are:

1. Friction between the tyres of a vehicle and the road makes it possible for the vehicle to move forward safely.
2. Friction between chalk and a blackboard allows teachers to write clearly on the board.

The two disadvantages of friction are:

1. Friction makes it difficult to slide heavy objects across the floor, so more effort is needed to move them.
2. Friction produces heat, which can cause wear and damage to machine parts such as brakes or bearings.

Ques 10: What is a lever? Describe the three types with examples.
Ans: A lever is a rigid rod arranged so that it can move freely around a fixed point. It has three main parts:

1. Fulcrum: The fixed point around which the rod turns.
2. Load: The object on which work is to be done.
3. Effort: The force applied to move the load.

First-class lever:
In a first-class lever the fulcrum is between the load and the effort. It can change the direction of the applied force and can give a mechanical advantage depending on positions.
Eg: A pair of scissors, a seesaw and a crowbar.

Second-class lever:
In a second-class lever the load is between the fulcrum and the effort. These levers make it easier to lift heavy loads.
Eg: A wheelbarrow, a bottle opener and a nutcracker.

Third-class lever:
In a third-class lever the effort is between the fulcrum and the load. These levers increase the speed or distance of the load but need a larger effort.
Eg: A stapler, forceps, fishing rods and ice tongs (chimta).

Ques 11: What is a wheel and axle? Give examples.
Ans: A wheel and axle is a simple machine made of a wheel rigidly attached to a rod called an axle. When the wheel is turned, the axle turns with it. This arrangement helps in moving or lifting loads more easily.
Eg: A crank used to raise a bucket from a well, a screwdriver, a door knob and the steering wheel of a car.

Ques 12: What is a pulley? What are its different types? Give examples.
Ans: A pulley is a wheel with a grooved rim over which a rope, chain or belt runs. The wheel turns around a fixed axle. Pulleys are used to change the direction of a force or to lift heavy loads more easily.

Fixed pulley:
The axle of a fixed pulley is attached to a support such as a hook or a wall. A fixed pulley changes the direction of the force and makes some tasks easier.
 Eg: Lifting a bucket from a well or raising a flag on a flagpole.

Movable pulley:
The axle of a movable pulley is not fixed; it moves with the load. A movable pulley reduces the effort needed to lift a heavy load and is often used together with a fixed pulley.
Eg: A crane often uses a combination of fixed and movable pulleys to lift heavy objects.

Ques 13: List any two advantages and two disadvantages of friction.
Ans: The two advantages of friction are -

1. Friction between vehicle tyres and the road allows vehicles to move forward safely and to stop when needed.
2. Friction between chalk and the blackboard makes writing possible and clear.

The two disadvantages of friction are -

1. Friction makes it hard to slide heavy objects across the floor, requiring more effort.
2. Friction produces heat, which can cause wear and damage to machine parts such as brakes.

Ques 14: What is a lever? Describe its three types with examples.
Ans: A lever is a rigid rod arranged so that it can turn about a fixed point. It has three parts:

1. Fulcrum - The fixed point around which the rod moves.
2. Load - The object on which work is to be done.
3. Effort - The force applied to the rod to do the work.

First-class lever: The fulcrum is between the load and the effort. Eg. - A pair of scissors, a seesaw and a crowbar.
Second-class lever: The load is between the fulcrum and the effort. Eg. - A wheelbarrow, a bottle opener and a nutcracker.
Third-class lever: The effort is between the fulcrum and the load. Eg. - A stapler, forceps, fishing rods and ice tongs (chimta).

Ques 15: What is a wheel and axle? Give examples.
Ans: A wheel and axle is a wheel firmly attached to a rod called an axle so that both turn together. Turning the wheel turns the axle and this helps to move or turn objects more easily. Eg. - The crank used to raise a bucket from a well, a screwdriver, a door knob and the steering wheel of a car.