Class 8 Science Chapter 8 Practice Question Answers - Force and Pressure

Q1: What is the name of the instrument used to measure atmospheric pressure?
Ans: Barometer

Q2: Give two examples of contact force.
Ans:

• Muscular force
• Force of friction

Q3: Name the force exerted on a ball of dough to make a flat chapati.
Ans: Muscular force

Q4: What kind of force is an electrostatic force?
Ans: Non-contact force

Q5: Is the gravity a property of earth only?
Ans: No

Q6: Name the force due to which every object falls on earth.
Ans: Gravitational force

Q7: What do you mean by pressure?
Ans: Force per unit area (Force/Area)

Q8: Do liquids and gases also exert pressure?
Ans: Yes

Q9: We ___________ the bucket to take out water from well.
Ans: pull

Q10: The strength of a force is usually expressed by its ___________.
Ans: magnitude

Q11: ___________ force is the force resulting due to the action of muscles.
Ans: Muscular

Q12: The envelop of air all around us is called ___________.
Ans: atmosphere

Q13: To open a door we or ___________ the door.
Ans: push, pull

Q14: Force of friction is an example of ___________ force.
Ans: contact

Q15: The pressure which is exerted by air around us is known as
(a) force
(b) atmospheric pressure
(c) muscular force
(d) friction
Ans: (b)
Explanation: Atmospheric pressure is the pressure exerted by the weight of the Earth's atmosphere on objects at or near the surface of the Earth. It is a result of the air molecules in the atmosphere pressing down on everything beneath them due to gravity.

Q16: Force acting on per unit area is called
(a) non-contact forces
(b) contact forces
(c) force
(d) pressure
Ans: (d)
Explanation: Pressure is the force exerted per unit area. It is calculated by dividing the force applied on a surface by the area over which the force is distributed. Mathematically, pressure (P) is defined as P = F / A, where F is the force and A is the area.

Q17: A ___________ exerted by an object on another is a force.
(a) Push or pull
(b) Contact or non-contact force
(c) Pressure
(d) Magnitude
Ans: (a)
Explanation: A force is a push or pull that one object exerts on another. It can cause an object to accelerate, decelerate, or change direction.

Q18: The force exerted by the earth to pull the object towards itself is called
(a) electrostatic force
(b) gravitational force
(c) muscular force
(d) contact force
Ans: (b)
Explanation: Gravitational force, also known as gravity, is the force of attraction between two masses. The Earth's gravitational force pulls objects toward its center, giving them weight and keeping them anchored to its surface.

Q19: Muscular force is also called ___________ force.
(a) non-contact
(b) contact
(c) gravitational
(d) magnetic
Ans: (b)
Explanation: Muscular force is a type of contact force. Contact forces are those forces that occur when two objects are physically in contact with each other. Muscular force is the force exerted by muscles on objects, and it is a common example of a contact force.

Value-Based Questions

Q20: On Lokesh’s birthday Shreya was given charge to amuse children with some little tricks. Shreya sticked balloons to the wall by just rubbing them in her clothes. She bent the water stream from a tap without touching it. She did so by bringing big balloon near to the flowing water. All children were very happy on seeing this little magic. Everybody praised Shreya.

1. How do balloons stick to walls?
2. How Shreya bent the water stream by bringing a big balloon near it and without touching it?
3. What values of Shreya is shown here?

Ans:

1. On rubbing the balloon with hair or clothes, it acquire negative charges. The negative charges are attracted to the positive charges on the wall and balloon sticks to the wall.
2. Negative charge on the balloon attracts positive charge on water molecules. Thus, bent the water molecules.
3. Shreya is dutiful, friendly with scientific aptitude.