Force and Pressure Class 8 Extra Questions and Answers Science Chapter 11

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In this page, we are providing Force and Pressure Class 8 Extra Questions and Answers Science Chapter 11 pdf download. NCERT Extra Questions for Class 8 Science Chapter 11 Force and Pressure with Answers will help to score more marks in your CBSE Board Exams.

Class 8 Science Chapter 11 Extra Questions and Answers Force and Pressure

Extra Questions for Class 8 Science Chapter 11 Force and Pressure with Answers Solutions

Force and Pressure Class 8 Extra Questions Very Short Answer Type

Question 1.
What is the name of the instrument used to measure atmospheric pressure?
Answer:
Barometer

Question 2.
Give two examples of contact force.
Answer:

  • Muscular force
  • Force of friction

Question 3.
Name the force exerted on a ball of dough to make a flat chapati.
Answer:
Muscular force

Question 4.
What kind of force is an electrostatic force?
Answer:
Non-contact force

Question 5.
Is the 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 do you mean by pressure?
Answer:
Force per unit area (Force/Area)

Question 8.
Do liquids and gases also exert pressure?
Answer:
Yes

Question 9.
What are the two states of motion?
Answer:

  • The state of rest.
  • The state of motion.

Question 10.
What kind of force is friction?
Answer:
Contact force

Question 11.
What type of force is gravitational force?
Answer:
Non-contact force

Question 12.
Is it true that force acting on an object can also change its shape?
Answer:
Yes, it is true.

Question 13.
While sieving grains, small pieces fall down. Which force pulls them down?
Answer:
Gravitational force

Question 14.
How can we change the speed and the direction of a moving body?
Answer:
By applying force.

Question 15.
What is the distance moved by an object in unit time called?
Answer:
Speed

Question 16.
Does force of gravity act on dust particles?
Answer:
Yes

Question 17.
Does the force of gravitation exist between two astronauts in space?
Answer:
Yes

Question 18.
What is a force?
Answer:
A push or pull on an object is called force.

Question 19.
What is the SI unit of pressure?
Answer:
Pascal (Pa)

Question 20.
At least how many objects are needed to apply a force?
Answer:
At least two objects are needed to apply a force.

Question 21.
Give one example of gravitational force.
Answer:
An apple falling from the tree to ground.

Question 22.
What is meant by atmospheric pressure?
Answer:
The weight of air acting per unit area is known as atmospheric pressure.

Question 23.
What do you mean by magnitude?
Answer:
The strength of a force is usually expressed by its magnitude.

Question 24.
What is muscular force?
Answer:
The force resulting due to the action of muscles is known as muscular force.

Question 25.
What is contact force?
Answer:
Force that can be applied only when it is in contact with an object is called contact force.

Question 26.
What do you mean by the term atmosphere?
Answer:
The envelope of air all around us is known as atmosphere.

Force and Pressure Class 8 Extra Questions Short Answer Type

Question 1.
Define pressure.
Answer:
The force acting per unit surface area is called pressure. SI unit of pressure is measured in Newton/ Metre2, which is equal to 1 Pascal (Pa).

Question 2.
How do fluids exert pressure?
Answer:
Fluids exert pressure in all directions. Fluids also exert pressure on the walls of the container that hold them.

Question 3.
A force of 100 N is applied on an area of 4 m2. Compute pressure being applied on the area.
Answer:
Given: Force = 100 N, Area = 4 m2

Force and Pressure Class 8 Extra Questions and Answers Science Chapter 11 .1

Question 4.
Which force is responsible for downward movement of a parachutes? Will he come down with the same speed without the parachute?
Answer:
Force of gravity is responsible for this downward movement. No, without parachute he will come down with a higher speed.

Question 5.
Two thermocol balls held close to each other move away from each other. When they are released, name the force which might be responsible for this phenomenon. Explain.
Answer:
Electrostatic force is responsible for this phenomenon. The two balls have similar charges, that’s why they move away due to repulsion between them.

Question 6.
How does an applied force changes 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 applied in the direction opposite to the motion, then it decreases the speed of the object.

Question 7.
Name the forces acting on the car sticking 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 8.
What is the similarity between electrostatic and magnetic forces?
Answer:

  • Both are non-contact forces.
  • Both are attractive as well as repulsive forces.

Question 9.
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.

Force and Pressure Class 8 Extra Questions Long Answer Type

Question 1.
What is force? State the difference between contact force and non-contact force. A push or pull on an object is called a force.
Answer:

Contact force Non-contact force
Force that can be applied only when it is in contact with an object is called a contact force, e.g., muscular force, frictional force The force exerted on an object without touching it is known as non-contact force, e.g., gravitational force, magnetic force

Question 2.
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.
(a) Contact forces: When force is applied on an object by direct or indirect physical contact the applied force is called contact force. Muscular and frictional force are example of contact force.

  • Muscular force: The force resulting due to 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.

(b) Non-contact forces: When a force is applied to an object by another body that is not in direct contact with it is called non-contact force. Gravitational, magnetic and electrostatic force are example of non-contact force.

  • Gravitational force: The attractive force of the earth which acts upon all the 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 other magnet or magnetic material is known as magnetic force.

Question 3.
Why it is easier to walk on soft sand if we have flat shoes rather than shoes with sharp heels (or pencil heels)?
Answer:
A flat shoe has a greater area in contact with the soft sand and exerts less pressure on the soft ground. Due to this the ‘flat’ shoes do not sink much in soft sand and it is easy to walk on it. On the other hand, a sharp heel has a small area in contact with the soft sand and exerts a greater pressure on the sand. Due to this, the sharp heels sink deep into soft sand making it difficult for the wearer to walk on it.

Question 4.
What is pressure? What is the relation of pressure with area on which it is applied?
Answer:
Force exerted on per unit area is called pressure. Pressure is related with area on which it is applied. When the area is increased the pressure exerted is less. But when the area on which pressure is exerted is decrease the pressure increases. So we can conclude that pressure increases with decrease in area.
List the characteristics of pressure exerted by a liquid.

  • Liquid exerts pressure in all directions.
  • Pressure in liquid does not depends on shape, size and surface area of the container.
  • Pressure increases with depth.
  • All points at the same level in a liquid are at the same pressure.
  • Pressure does not depend on the surface of the immersed object.

Force and Pressure Class 8 Extra Questions HOTS

Question 1.
We know that there is a huge amount of atmospheric pressure on us. But we do not experience its effect why?
Answer:
The pressure of air inside our body is same as that of the atmosphere. Therefore, we do not experience its effect

Question 2.
Why do sea divers wear specially designed suits?
Answer:
Since the pressure of liquid increases with the increasing depth of sea. Specially designed suits protect scuba divers from the huge pressure of the water underneath.Two persons are applying forces on two opposite sides of a moving cart. The cart still moves with the same speed in the same direction.

Question 3.
What do you infer about the magnitudes and direction of the forces applied?
Answer:
Both the persons are applying forces from opposite direction with equal magnitudes.

Question 4.
An archer shoots an arrow in the air horizontally. However, after moving some distance, the arrow falls to the ground. Name the initial force that sets the arrow in motion. Explain why the arrow ultimately falls down.
Answer:
The initial force is muscular force which sets the arrow in motion. The force of gravity that acts on the arrow in the downward direction brings it to the ground.

Question 5.
Two rods: A and B, having same weight and equal length have different thickness. Rod A is thinner while Rod B is thicker. They are held vertically on the surface of sand. Which one of them will sink more? Why?
Answer:
Rod A will go deeper as it has a smaller area of contact, therefore the same force produces more pres¬sure. In case of rod B the same force produces less pressure.

Question 6.
It is difficult to cut cloth using a pair of scissors with blunt blades. Explain.
Answer:
Blunt blades have larger area compared to the sharp-edged blades. Thus, the applied force produces a lower pressure in case of blunt blades, which makes it difficult to cut the cloth.

Question 7.
Observe the figures given below carefully.
Force and Pressure Class 8 Extra Questions and Answers Science Chapter 11 .2
Volume of water in each vessel is shown above. Arrange them in order of decreasing pressure at the base of each vessel. Explain the reason.
Answer:
Pressure of a liquid column depends upon the height of the liquid column and not on volume of the liquid. Decreasing order of pressure at the base of each vessel is B>D>A>C.

Force and Pressure Class 8 Extra Questions Value Based (VBQs)

Question 1.
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.

(a) How do balloons stick to walls?
(b) How Shreya bent the water stream by bringing a big balloon near it and without touching it?
(c) What values of Shreya is shown here?
Answer:
(a) 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.
(b) Negative charge on the balloon attracts positive charge on water molecules. Thus, bent the water molecules.
(c) Shreya is dutiful, friendly with scientific aptitude.