Forces And Laws Of Motions Test

Forces And Laws Of Motions

This is Forces and Laws of Motions Test-03 for CBSE class 09 Science.. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

Essential characteristic of equilibrium is

A
momentum equals zero
B
acceleration equals zero
Correct
C
K. E equals zero
D
none of these

To every action there is an,

A
Unequal and opposite reaction
B
None of the above
C
Equal and opposite reaction
Correct
D
Equal and no reaction

“Forces always occur in pairs”. From which law can we conclude the above statement?

A
Newton’s law of gravitation
B
Newton’s third law
Correct
C
New tons second law
D
Newton’s first law

Frictional force

A
always in the opposite director of motion
B
always opposes relative motion between the surfaces of contact
Correct
C
always in the direction of motion
D
always opposes motion of a body

‘Any two forces which are equal and opposite form an action and reaction pair’ The above statement is

A
partially false
B
true
Correct
C
false
D
partially true

“Action and reaction are equal and opposite but even then they do not cancel each other” the above statement is

A
partially true
B
false
C
partially false.
D
true
Correct

Find the incorrect statement about Newton’s law of action and reaction. Action and reaction

A
are equal in magnitude
B
act on same bodies
Correct
C
are different in direction
D
act simultaneously

Which is incorrect statement about action and reaction referred to Newton’s third law of motion? A They are not equal B They are opposite C They act on same object D They act simultaneously

A
All of these
B
(a), (b) and (c) are correct
C
(a) and (c) are correct
Correct
D
(b) and (c) are correct

Which of the following is not used to reduce friction

A
using ball bearing
B
using grease between contact surfaces
C
using oil between contact surfaces
D
making scratches on the contact surfaces
Correct

What is the momentum of an object of mass \(\frac{1}{2}\)m, moving with a velocity 2v?

A
\({\left( {mv} \right)^2}\)
B
mv
Correct
C
\(\frac{1}{2}m{v^2}\)
D
\(m{v^2}\)

“Internal forces are forces which bodies exert on each other when the bodies are part of the system” is

A
true
Correct
B
false
C
partially false
D
partially true

According to the law of conservation of momentum

A
\({{\text{m}}_{\text{1}}}{{\text{u}}_{\text{1}}}{\text{ }} + {\text{ }}{{\text{m}}_{\text{2}}}{{\text{u}}_{\text{2}}} = {\text{ }}{{\text{m}}_{\text{1}}}{{\text{v}}_{\text{1}}}{\text{ }} + {\text{ }}{{\text{m}}_{\text{2}}}{{\text{v}}_{\text{2}}}{\text{ }}\)
Correct
B
\({{\text{m}}_{\text{1}}}{{\text{u}}_{{\text{1 }}}} + {\text{ }}{{\text{m}}_{\text{1}}}{{\text{u}}_{{\text{1}} = }}{\text{ }}{{\text{m}}_{\text{2}}}{{\text{v}}_{\text{2}}}{\text{ }} + {\text{ }}{{\text{m}}_{\text{2}}}{{\text{v}}_{\text{2}}}\)
C
None of the above
D
\({{\text{m}}_{\text{1}}}{{\text{u}}_{\text{1}}} - {{\text{m}}_{\text{2}}}{{\text{u}}_{{\text{2 }}}} = {{\text{m}}_{\text{1}}}{{\text{v}}_{\text{1}}} - {{\text{m}}_{\text{2}}}{{\text{v}}_{\text{2}}}\)

A bullet of mass 10g is fired from a rifle. The bullet tales 0.003 second to move through its barrel and leaves it with a velocity of 300m|s. What is the force exerted on the bullet by the rifle?

A
200N
B
300N
Correct
C
400N
D
250N

A force of 5N gives a mass m1 an acceleration of 10ms-2 and mass m2 an acceleration of \({\text{2}}0{\text{m}}{{\text{s}}^{ - {\text{2}}}}\).What acceleration would if give it both the masses were tied together?

A
\({\text{7}}.{\text{65m}}{{\text{s}}^{ - {\text{2}}}}{\text{ }}\)
B
\({\text{6}}.{\text{67m}}{{\text{s}}^{ - {\text{2}}}}{\text{ }}\)
Correct
C
none of these
D
\({\text{7}}.00{\text{m}}{{\text{s}}^{ - {\text{2}}}}{\text{ }}\)

Statement A: Rocket contains fuel as well as oxygen to burn its fuel in its body. Statement B: A jet plane takes oxygen from atmosphere to burn its fuel

A
neither statement A nor statement B is true
B
both the statement a and b are true
Correct
C
statement A is true
D
statement B is false