Students can keep Class 8 Science Extra Questions and Class 8th Curiosity Chapter 5 Exploring Forces Important Extra Question Answer handy for quick reference during exams.
Class 8 Science Chapter 5 Exploring Forces Extra Questions
Class 8 Science Chapter 5 Extra Questions on Exploring Forces
Exploring Forces Class 8 Very Short Question Answer
Question 1.
What is a force?
Answer:
A push or pull on an object is called force.
Question 2.
How many objects are needed to apply a force?
Answer:
At least two objects are needed to apply a force.
Question 3.
What is muscular force?
Answer:
The force resulting from the action of muscles is known as muscular force.
Question 4.
What is contact force?
Answer:
A force that can be applied only when it is in contact with an object is called a contact force.
Question 5.
Is gravity a property of Earth only?
Answer:
No
Question 6.
Name the force due to which every object falls on Earth.
Answer:
Gravitational force
Question 7.
What kind of force is friction?
Answer:
Contact force
Question 8.
What type of force is gravitational force?
Answer:
Non-contact force
Question 9.
Is it true that force acting on an object can also change its shape?
Answer:
Yes, it is true.
Question 10.
While sieving grains, small pieces fall. Which force pulls them down?
Answer:
Gravitational force
Question 11.
How can we change the speed and the direction of a moving body?
Answer:
By applying force.
Question 12.
Give two examples of contact force.
Answer:
- Muscular force
- Force of friction
Question 13.
Name the force exerted on a ball of dough to make a flat chapati.
Answer:
Muscular force
Question 14.
What kind of force is an electrostatic force?
Answer:
Non-contact force
Question 15.
Give one example of gravitational force.
Answer:
An apple falling from the tree to the ground.
Question 16.
What will be the net force on an object when two forces act on an object in the same direction?
Answer:
Forces applied on an object in the same direction add to one another.
Question 17.
During dry weather, clothes made of synthetic fibre often stick to the skin. Which type of force is responsible for this phenomenon? (NCERT Exemplar)
Answer:
Magnetic force
Question 18.
Does the force of gravitation exist between two astronauts in space? (NCERT Exemplar)
Answer:
Yes
Question 19.
A ball of dough is rolled into a flat chapatti. Name the force exerted to change the shape of the dough. (NCERT Exemplar)
Answer:
Muscular force.
Question 20.
Where do we apply a force while walking? (NCERT Exemplar)
Answer:
While walking, we apply force on the ground.
Question 21.
Does the force of gravity act on dust particles? (NCERT Exemplar)
Answer:
Yes
Question 22.
A gas-filled balloon moves up. Is the upward force acting on it larger or smaller than the force of gravity? (NCERT Exemplar)
Answer:
Upward force is larger than the force of gravity.
Question 23.
What happens when the two forces act in the opposite direction on an object?
Answer:
If two different forces act in opposite directions on an object, the net force acting on it is the difference between the two forces.
Exploring Forces Class 8 Short Question Answer
Question 1.
How does an applied force change the speed of an object?
Answer:
If the applied force is in the direction of motion, the speed of the object increases. But if the force is applied in the direction opposite to the motion, then it decreases the speed of the object.
Question 2.
What is the similarity between electrostatic and magnetic forces?
Answer:
- Both are non-contact forces.
- Both are attractive as well as repulsive forces.
Question 3.
What are the effects of force on an object?
Answer:
- Force can change the state of motion of an object.
- Force changes the speed of a moving object.
- Force can cause an object to turn or change direction.
- Force can change the shape of an object.
Question 4.
Two thermocol balls held close to each other move away from each other. When they are released, name the force that might be responsible for this phenomenon. Explain.
Answer:
Electrostatic force is responsible for this phenomenon. The two balls have similar charges, which is why they move away due to repulsion between them.
Question 5.
Name the forces acting on the car stuck to an electromagnet in a Junkyard. Which one of them is larger?
Answer:
Magnetic force (in the upward direction) and force of gravity or the weight of the car (downward).
Magnetic force is larger than the force of gravity.
Question 6.
Which force is responsible for the downward movement of a parachute? Will he come down with the same speed without the parachute?
Answer:
The force of gravity is responsible for this downward movement. No, without a parachute, he will come down at a higher speed.
Question 7.
What may be the consequences when a force is applied to an object?
Answer:
When a force is applied to an object, the consequence will be a
- change in the shape of the object.
- change in the state of motion of the object.
Question 8.
A girl is pushing a box towards the east. In which direction should her friend push the box so that it moves faster in the same direction? (NCERT Exemplar)
Answer:
Towards the east.
Question 9.
What can be the result of a force applied to an object?
Answer:
Force applied to an object may result in:
- change in the shape of the object.
- change in the direction of motion of an object.
- change in speed of an object if it is moving.
- movement of an object from rest.
- some or all of the above effects.
Question 10.
A chapati maker is a machine that converts balls of dough into chapatis. What effect of force comes into play in this process? (NCERT Exemplar)
Answer:
The force changes the shape of the dough.
Question 11.
What is muscular force? Why is it called a contact force?
Answer:
Muscular force: The force resulting from the action of muscles is known as muscular force. Since muscular force can be applied only when it is in contact with an object, it is also called a contact force.
Question 12.
Give three examples of forces exerted by muscles in our body.
Answer:
The three examples of muscular force in our body are:
- Blood circulation in our body.
- Inhalation and exhalation of air by the lungs.
- Running by the muscles of the legs.
Question 13.
Name some non-contact forces with examples.
Answer:
Some non-contact forces are:
- Gravitational force
Example: A ball projected upwards falls back on Earth. - Magnetic force
Example: The force exerted by a magnet on iron. - Electrostatic force
Example: Sticking an inflated balloon to the wall after rubbing it with a dry cloth.
Question 14.
Distinguish between contact forces and non-contact forces with examples.
Answer:
- Contact Force: A Force that can be applied only when it is in contact with an object is called a contact force.
Examples: muscular force, frictional force. - Non-contact force: The force exerted on an object without touching it is known as a non-contact force.
Examples: gravitational force, magnetic force.
Exploring Forces Class 8 Long Question Answer
Question 1.
Define the different types of forces.
Answer:
Force can act on a body from a distance or by being in contact with it. Depending on this, forces can be classified as contact and non-contact forces.
- Contact forces: When a force is applied to an object by direct or indirect physical contact, the applied force is called a contact force.
- Muscular and frictional forces are examples of contact forces.
- Muscular force: The force resulting from the action of muscles is known as the muscular force.
- Frictional force: The force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.
- Non-contact forces: When a force is applied to an object by another body that is not in direct contact with it is called a non-contact force.
- Gravitational, magnetic, and electrostatic forces are examples of non-contact forces.
- Gravitational force: The attractive force of the Earth, which acts upon all objects, is known as the force of gravity or just gravity.
- Electrostatic force: The force exerted by a charged body on another charged or uncharged 1 body is known as electrostatic force.
- Magnetic force: The force exerted between a magnet and another magnet or magnetic material is known as magnetic force.
Question 2.
Define force. What are its effects on objects?
Answer:
A force is a push or pull upon an object resulting from its interaction with another object. It has both magnitude and direction, making it a vector quantity. The unit of force is Newton (N), named after Isaac Newton.
Effects of force:
- Motion change: A stationary object may begin to move; a moving object may stop or change speed.
- Direction change: Force can alter the direction of a moving object.
- Shape change: Some forces deform objects, such as squashing or stretching them.
Examples:
- Kicking a football (starts motion)
- Applying brakes (stops motion)
Question 3.
Prove that the force of friction depends on the nature of the two surfaces in contact.
Answer:
Collect the following things: A thick book, nylon cloth, gunny cloth, plastic sheet, jute cloth, and sandpaper. Place the book on each of the materials and slide it on the floor one by one. If our book slides off the plastic sheet or nylon cloth, use adhesive tape to stick it firmly on the surface of the book. We will observe that the different materials offer different amounts of resistance to sliding. This activity shows that the force of friction depends on the nature of the surface in contact. In general, a smooth surface offers less friction than a rough surface.
Exploring Forces Class 8 Case Based Questions
Read the given passage below and answer the question:
In a game of volleyball, players often push the moving ball to their teammates to make a winning move. Sometimes the ball is returned to the other side of the court by pushing or smashing it. In cricket, a batsman plays his or her shot by applying a force on the ball with the bat.
Question 1.
What kind of force is applied by a batsman on a ball while hitting it?
(a) Magnetic Force
(b) Muscular Force
(c) Frictional Force
(d) Gravitation Force
Answer:
Option (b) is correct.
Explanation: While hitting a ball, the force is caused by the action of muscles in the batsman’s body. The force resulting from the action of muscles is known as the muscular force.
Question 2.
Force can be defined as:
(a) Work done
(b) Energy required to do work
(c) Push or Pull
(d) Push only
Answer:
Option (c) is correct.
Explanation: A push or a pull on an object is called a force.
Question 3.
In the given example of a volleyball game, what changes in force were brought about on the volleyball?
(a) Change in direction of motion
(b) Change in shape
(c) Change in state of motion
(d) Both Option (a) and (c)
Answer:
Option (a) and (c)
Explanation: When players hit the volleyball, its speed changes, and also the direction of its motion changes.
Exploring Forces Extra Questions for Practice
Question 1.
What is force?
Question 2.
Name the SI unit of force.
Question 3.
Give one example of a contact force.
Question 4.
What kind of force is gravity?
Question 5.
What causes a ball to stop rolling on the floor?
Question 6.
Name the various types of forces.
Question 7.
What is the necessary condition for a force to come into play?
Question 8.
What can be the result of a force applied on an object?
Question 9.
What happens to the springs of a sofa when we sit on it?
Question 10.
What is muscular force?
Question 11.
Define the force of friction.
Question 12.
What is electrostatic force?
Question 13.
Define contact and non-contact forces with examples.
Question 14.
How does friction affect motion?
Question 15.
Why do objects fall to the ground when dropped?
Question 16.
What is the role of muscular force in daily life?
Question 17.
Explain how force can change the shape of an object.
Question 18.
Based on the interaction, what are the two categories of forces?
Question 19.
What will be the net force on an object when two forces act on an object in the same direction?
Question 20.
What are non-contact forces? Write the different types of non-contact forces.
Question 21.
Describe different types of forces with suitable examples.
Question 22.
Explain how force can change the state of motion and shape of an object.
Question 23.
Discuss the effects of friction and how it can be both helpful and harmful.
Question 24.
Compare gravitational, magnetic, and electrostatic forces.
Question 25.
Why do we experience less pressure when wearing flat shoes on sand compared to pencil heels?
Question 26.
Read the given passage below and answer the questions.
A force may make an object move from rest. It may change the speed of an object if it is moving. It may change the direction of motion of an object. It may bring about a change in the shape of an object. It may cause some or all of these effects. While a force may cause one or more of these effects, it is important to remember that none of these actions can take place without the action of a force.
(a) What will happen if force is applied to an object at rest?
(b) What are some possible effects when force is applied to any object?
(c) Can any of the actions mentioned here occur without the action of a force?
Question 27.
Read the given passage below and answer the questions.
The force of friction always acts on all the moving objects, and its direction is always opposite to the direction of motion. Since the force of friction arises due to contact between surfaces, it is also an example of a contact force.
(a) On which object does friction work?
(b) How is the friction generated?
(c) Is friction a contact force? Explain.