Force and Motion Class 4 SCIENCE - Orchids

# Force and Motion for Class 4 Science

• A push or pull applied to an object can be termed a force.
• Effects of forces are as follows:
• Bring an object to rest into motion or change the speed of a moving object.
• Change the shape of an object.
• Change the direction of an object.
• Motion can be defined as an act of change in the position of an object. Motion can be uniform or non-uniform, based on the distance covered in the specific time interval.
• Based on the type of path of motion, it can be circular or rectilinear.
• This concept is about types of force and motion.

## Question 1:

### What Kind of Quantity Is Force?

• Force is a vector quantity
• The quantities that have both magnitude and direction are called vector quantities.

## Question 2:

Categorize the Following Into Types of Forces.

1. Inertia
2. Force Exerted by a Charged Body on Another Charged or Uncharged Body.
3. The Force That Pulls Every Object Towards the Earth.
4. The Force That Attracts a Fridge Magnet Towards the Wall of the Fridge.
5. The Force That Helps in Skiing.
6. The Force That Is Applied on a Hand Pump to Collect Water.

1. Not a force.
2. Electrostatic force.
3. Gravitational force.
4. Magnetic force.
5. Frictional force.
6. Mechanical force.

## Question 3:

### What Is Inertia?

• Inertia is the property of an object by virtue of which it either remains in a static state or uniform motion.
• Uniform motion can be defined as the motion of an object where it covers equal distances in equal time intervals.

## Question 4:

### What for Sir Isaac Newton is Famous?

• Sir Isaac Newton was a famous scientist who worked on force and gravity.
• He invented calculus and the theory of universal gravity and coined three laws of motion.
• He also invented the reflecting telescope that can form an image with the help of reflecting mirrors.

## Question 5:

### What Is Centrifugal Force? Give Examples.

• The centrifugal force is an apparent force felt on an object when moving in a circular path.
• Example- Sensation of force felt while we sit in a merry-go-round moving in a circular direction is due to the centrifugal force.

## Question 6:

Arrange the Following Animals in Ascending Order According to Their Inertia.

### Why is the magnitude of inertia different among all these animals?

• Inertia exerted by a body or object is directly proportional to its mass.
• The more the mass, the more inertia is exerted by it.
• Hence, the order of the animals in ascending sequence would be Ant< Caterpillar< Lizard< Cat< Bear< Elephant.

## Question 7:

### Why Are Bogies of Trains Provided With Buffers?

• Bogies of trains are provided with buffers because those increase the impact of jerking between two bogies, preventing the sudden jerking of the passengers sitting inside.

## Question 8:

### Why Do Two Thermocol Balls Always Move Away From Each Other?

• Two thermocol balls move away from each other because electrostatic force acts on those balls.
• As both balls have similar charges in their bodies, they repel each other.

## Question 9:

### What Are the Poles of a Magnet?

• The ends of the magnet are termed poles.
• A magnet has two poles, a north pole and a south pole.
• The same poles of a magnet repel each other.
• The opposite poles of a magnet attract each other.

## Question 1:

See the Picture and Answer the Following Questions-

1. Which Point Has the Highest Sideways Pressure?
2. Which Point Has the Lowest Sideways Pressure?
3. What Will Happen to the Lateral Pressure of C if the Water Level Is Reduced?
4. How Can the Magnitude of Pressure Be Increased at the Bottom of a Container Half-Filled With a Liquid?

1. Point C has the highest sideways pressure.
2. Point A has the lowest lateral pressure.
3. The lateral pressure will reduce at point C if the water level is reduced.
4. If a container is half-filled with a liquid, the pressure at the bottom can be increased by pouring more liquid into that container.

The height of liquid inside a container is directly proportional to the pressure at the bottom of the container.

## Question 2:

A Force of 400 N Is Applied to an Area of 4 m2. Calculate the Pressure Applied to the Site.

• The pressure applied to the area will be:
Pressure= Force/ Area that means 400/4 = 100 Pascal.

## Question 3:

### What Is the Formula of Pressure in the S.I. Unit?

• The formula of pressure in the S.I. unit is- Pressure = Force/ Unit Area = N/ m2 i.e. Newton per metre square.

## Question 4:

Identify the types of motions in the following images-

1. The motion of a satellite- Circular motion.
2. The motion of a moving car- rectilinear motion.
3. The motion of a swing- Periodic motion.

## Question 5:

### What is revolution of the Earth?

• The rotation of Earth around the sun in a circular orbit is called revolution.
• One revolution takes 365.26 days to complete.

## Question 1:

Give three examples of levers that we use in our daily life and mention their class.

Three levers that we use in our daily life are-

• Plier: Class I lever.
• Scissors: Class I lever.
• Wheelbarrow: Class II lever.