Laws of Motion Exe-3C Linear Momentum Newton’s Second Law Very Short Answer Type for Class-9 ICSE Concise Physics. There is the solutions of Very short Answer type Questions of your latest textbook which is applicable in 2023-24 academic session. Visit official Website CISCE for detail information about ICSE Board Class-9.
Laws of Motion Exe-3C Linear Momentum Newton’s Second Law Very Short Answer
(ICSE Class – 9 Physics Concise Selina Publishers)
Board | ICSE |
Class | 9th |
Subject | Physics |
Writer / Publication | Concise selina Publishers |
Chapter-3 | Laws of Motion |
Exe – 3C | Linear Momentum Newton’s Second Law |
Topics | Solution of Exe-3(C) Very Short Answer Type |
Academic Session | 2023-2024 |
Exe-3C Linear Momentum Newton’s Second Law Very Short Answer Type
Ch-3 Laws of Motion Physics Class-9 ICSE Concise
Page 77
Question 1. Define linear momentum and state its S.I. unit.
Answer :
Linear momentum of a body is the product of its mass and velocity.
Its SI unit is kgms-1.
Question 2. A body of mass m moving with a velocity v is acted upon by a force. Write an expression for change in momentum in each of the following cases: (i) When v <<c, (ii) When v →c and (iii) When v << c but m does not remain constant. Here, c is the speed of light.
Answer :
(i) When v <<c,
p = (mv) = mv
(ii) When v →c
p = (mv)
(iii) When v << c but m does not remain constant.
p = (mv)
Question 3.Two bodies A and B of same mass are moving with velocities v and 2v, respectively. Compare their (i) inertia and (ii) momentum.
Answer:
(i) Mass is the measure of inertia.
Let ‘m’ be the mass of the two bodies.
Inertia of body A:Inertia of body B :: m:m
Or, Inertia of body A:Inertia of body B :: 1:1
(ii)
Momentum of body A = m (v)
while Momentum of body B = m (2v) = 2mv
hence Momentum of body A:Momentum of body B :: mv:2mv
Or, Momentum of body A:Momentum of body B :: 1:2.
Question 4. Two balls A and B of masses m and 2 m are in motion with velocities 2v and v, respectively. Compare:
(i) Their inertia.
(ii) Their momentum.
(iii) The force needed to stop them in the same time.
Answer:
(i) Inertia of body A:Inertia of body B :: m:2m
Or, Inertia of body A:Inertia of body B :: 1:2.
(ii)
Momentum of body A = m ( 2v) = 2mv
and Momentum of body B = (2m) v = 2mv
Hence Momentum of body A:Momentum of body B :: 2 mv:2mv
Or, Momentum of body A:Momentum of body B :: 1:1.
(iii) According to Newton’s 2nd law of motion, rate of change of momentum is directly proportional to the force applied on it. Therefore,
Force needed to stop A:Force needed to stop B :: 1:1.
(Laws of Motion Exe-3C Very Short Class-9 ICSE)
Question 5. Name the S.I. unit of force and define it.
Answer:
The S.I. unit of force is newton.
One newton is the force which acts on a body of mass 1kg and produces an acceleration of 1 m/s2, i.e. 1 N = 1 kg × 1 m/s2.
Question 6. What is the C.G.S. unit of force? How is it defined?
Answer:
The C.G.S. unit of force is dyne.
One dyne is the force which acts on a body of mass 1 gramme and produces an acceleration of 1 cms-2, i.e. 1 dyne = 1 g × 1 cms-2.
Question 7. Name the S.I. and C.G.S. units of force. How are they related?
Answer:
The S.I. unit of force is newton and the C.G.S. unit of force is dyne.
1 N = 105 dyne.
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