Q26
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A disc of mass 2 kg is kept floating horizontally in air by firing bullets of mass 0.1 kg each vertically at it, at the rate of 5 per second. If the bullets rebound with the same speed, the speed with which these are fired will be-
A.
$1\cdot 96\mathrm{m / s}$
B.
$0\cdot 98\mathrm{m / s}$
C.
$9\cdot 8\mathrm{m / s}$
D.
$19.6\mathrm{m / s}$
Q27
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
For a body of 25 kg mass, the velocity-time graph is shown in figure. The force acting on the body is :
A.
$25\mathrm{N}$
B.
$50\mathrm{N}$
C.
$12.5\mathrm{N}$
D.
$100\mathrm{N}$
Q28
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A 2 kg toy car starts from rest (i.e. at t = 0, v = 0) can move along x-axis. Graph shows force $F_{x}$ , acting on the car. The velocity of the car at t = 10 s is :-
A.
$2\mathrm{m / s}$
B.
$6\mathrm{m / s}$
C.
$6.5\mathrm{m / s}$
D.
$5\mathrm{m / s}$
Q29
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
Force-time graph for the motion of a body is shown in fig. Change in linear momentum between 0 to 8 s is :-
A.
Zero
B.
4 N-s
C.
8 N-s
D.
6 N-s
Q30
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A body of mass 2 kg has an initial speed 5 ms $^{-1}$ . A force acts on it for some time in the direction of motion. The force-time graph is shown in figure. The final speed of the body is :-
A.
$9.25 \mathrm{ms} ^ {- 1}$
B.
$5 \mathrm{ms} ^ {- 1}$
C.
$14.3 \mathrm{ms} ^ {- 1}$
D.
$4.25 \mathrm{ms} ^ {- 1}$
Q31
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
Which one of the following statements is not true?
A.
The same force for the same time causes the same change in momentum for different bodies.
B.
The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts.
C.
A greater opposing force is needed to stop a heavy body than a light body in the same time, if they are moving with the same speed.
D.
The greater the change in the momentum in a given time, the lesser is the force that needs to be applied.
Q32
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
If force F = 50 - 20t, then impulse in interval [0, t] :-
A.
$50t - 10t^{2}$
B.
50t - 10
C.
$50 - t^{2}$
D.
$25t^{2}$
Q33
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
In the figure given below, the position-time graph of a particle of mass 0Ā·1 kg is shown. The impulse at t=2 sec is -
A.
$0\cdot 2\mathrm{kg - m / s}$
B.
$-0\cdot 2\mathrm{kg - m / s}$
C.
$0\cdot 1\mathrm{kg - m / s}$
D.
$-0\cdot 4\mathrm{kg - m / s}$
Q34
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
Gravel is dropped onto a conveyor belt at a rate of 1.5 kg/s. The extra force required in newton to keep the belt moving at 3 m/s is :-
A.
1.5 N
B.
2 N
C.
4 N
D.
4.5 N
Q35
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A block of metal weighing 1.5 kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of 3 kg/s with a speed of 10 m/s. The initial acceleration of the block will be :-
A.
20 m/sĀ²
B.
5 m/sĀ²
C.
10 m/sĀ²
D.
15 m/sĀ²
Q36
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A block of metal weighing 2 kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of 1 kg/s and a speed of 5 m/s. The initial acceleration of the block will be:-
A.
$2.5 \, m/s^{2}$
B.
$5 \, m/s^{2}$
C.
$10 \, m/s^{2}$
D.
$20 \, m/s^{2}$
Q37
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
If the force on a rocket moving in force free space with an exhaust velocity of gases 400 m/sec is 300N, then the rate of combustion of the fuel, is :-
A.
1.3 kg/s
B.
0.75 kg/s
C.
2.7 kg/s
D.
0.3 kg/s
Q38
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A satellite in force free space sweeps stationary interplanetary dust at a rate $(\mathrm{dM}/\mathrm{dt}) = +\alpha v^{2}$ . Here v is the velocity. The acceleration of satellite of mass M is:
A.
$-2\alpha v^{2}/M$
B.
$-3\alpha v^{2}/M$
C.
$-\alpha v^{3}/M$
D.
$-\alpha v^{2}$
Q39
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A rocket of mass 60 kg. is fired in a gravity free space is ejecting gases with velocity 300 m/s at the rate of 2 kg/s. What will be the initial acceleration of the rocket?
A.
$30 \, m/s^{2}$
B.
$5 \, m/s^{2}$
C.
$10 \, m/s^{2}$
D.
$15 \, m/s^{2}$
Q40
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
For a Rocket propulsion velocity of exhaust gases relative to rocket is 1.6 km/s. If mass of rocket system is 800 kg, then the rate of fuel consumption for a rocket to rise up with an acceleration $4.2 \, m/s^{2}$ will be :-
A.
12.25 kg/s
B.
17.5 kg/s
C.
7 kg/s
D.
5.2 kg/s
Q41
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
The force on a rocket, moving in gravity free space is 210 N. If the gases ejects from the rocket with speed 300 m/s (w.r.t. rocket) then the rate of combustion of the fuel is:
A.
$0.07\mathrm{kg}\mathrm{s}^{-1}$
B.
$1.4\mathrm{kg}\mathrm{s}^{-1}$
C.
$0.7\mathrm{kg}\mathrm{s}^{-1}$
D.
$10.7\mathrm{kg}\mathrm{s}^{-1}$
Q42
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A rocket of mass 800 kg is to be projected vertically upwards. The gases are exhausted vertically downwards with velocity 40 m/s with respect to the rocket. What is the minimum rate of burning fuel, so as to just lift the rocket upwards against the gravitational attraction? (Take g = 10 m/s $^{2}$ )
A.
80 kg/s
B.
400 kg/s
C.
200 kg/s
D.
800 kg/s
Q43
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A ball is moving towards the wall as shown in diagram then the momentum of the ball is conserved
A.
along the wall
B.
along the normal of the wall
C.
along any direction
D.
Both A and B
Q44
Allen
2. MOMENTUM RELATED PROBLEMS
MCQ
A water jet, whose cross sectional area is 'a' strikes a wall making an angle 'Īø' with the wall and rebounds elastically. The velocity of water of density 'd' is v. Force exerted on wall is :-
A.
$2\mathrm{av}^2\mathrm{d}\cos \theta$
B.
$2\mathrm{av}^2\mathrm{d}\sin \theta$
C.
$2\mathrm{avd}\cos \theta$
D.
$\mathrm{avd}\cos \theta$
Q45
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
Which figure represents the correct F.B.D. of rod of mass m as shown in figure :-
A.
B.
C.
D.
None of these
Q46
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
Working of rocket or jet is based on :-
A.
Newton's I law
B.
Newton's II law
C.
Newton's III law
D.
All the three laws
Q47
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
When a horse pulls a wagon, the force that causes the horse to move forward is the force
A.
He exerts on the wagon
B.
The wagon exerts on him
C.
The ground exerts on him
D.
He exerts on the ground
Q48
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
A man is at rest in the middle of a pond on perfectly smooth ice. He can get himself to the shore by making use of Newton's :-
A.
First law
B.
Second law
C.
Third law
D.
Law of gravitation
Q49
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
A material body A of mass m exerts a force on another material body B of mass 2m. If the acceleration of B be a, the magnitude of the acceleration of A is :-
A.
Zero
B.
a
C.
2a
D.
a/2
Q50
Allen
3. FBD, NEWTON'S THIRD LAW
MCQ
If the force of gravity suddenly increase, then:
A.
The mass of all bodies will increase
B.
The weight of all bodies will increase
C.
Both mass and weight of all bodies will increase
D.
Neither mass nor weight of all bodies will increase