A Block that is 12 cm wide, 7 cm long and 9 cm tall is kept on a table top which of its surface will exert a force minimum pressure. Its weight is 63 N. Calculate the pressure.
Answers
Answer:
Lakhmir Singh Science Class 8 Chapter 11 Very Short Answer Type Questions
Question 1
What is the push or pull on an object known as?
Answer:
Force
Force is a Pull or a push on the object.
Question 2.
Why do the shape and size of a balloon change when filled with air or water?
Answer:
As we know that air and water are the matter and matter has a characteristic property which says that they have mass and occupy certain space. So when air or water is filled in a balloon, they tend to stretch its rubber boundary and occupy the space. Therefore the shape and size of the balloon get change when filled with air or water.
Question 3.
Name the quantity whose unit is ‘Newton’ (N).
Answer:
Force
The unit of force is Newton. Kg ms-2 = Newton
Question 4.
When a ball is dropped from a height, its speed increases gradually. Name the force which causes this change in speed.
Answer:
Gravitational force
Every object in the universal exerts a force on every other object. this force is known as the gravitational force.
Question 5.
What is the unit of force?
Answer:
Newton
The unit of force is Newton
Question 6.
Give one example where force changes the shape of an object.
Answer:
When you squeeze a toothpaste.
Force can change the shape, size, direction, etc on applying the body.
Question 7.
Identify the actions involved in the following situations as push or pull, or both:
(a) Opening a drawer.
(b) A cricket ball hit by a batsman.
(c) Drawing a bucket of water from a well.
(d) moving a book placed on a table.
(e) A football player taking a penalty corner.
(f) Moving a wheel barrow.
Answer:
(a) PULL
Force is a Pull or a push on the object.
(b) PUSH
Force is a Pull or a push on the object.
(c) PULL
Force is a Pull or a push on the object.
(d) Ans Both push and pull
Pull or push on an object is known as force
(e) push
Pull or push on an object is known as force
(f) push
Pull or push on an object is known as force.
Question 8 A.
Name two contact forces.
Answer:
frictional force
applied force
The force applied when it is in contact with the object.
Question 8 B.
Name two non-contact forces.
Answer:
Gravitational force.
Magnetic force.
The force acting on an object without being in contact with it is known as non-contact force.
Question 9.
When a plastic pen is rubbed in dry hair, it attracts