IISER Physics - Newton's Laws of Motion
Exam Duration: 45 Mins Total Questions : 30
If a body of mass 3 kg is moving on a circular path with radius to 3m with a velocity of 2 \(ms^{-1}\) and acceleration of 1 \(ms^{-2}\). The ratio of normal force to ner force is
- (a)
0.8
- (b)
0.5
- (c)
0.6
- (d)
1.0
As stated in Q.No.26, the velocity of the centre of mass after separation is
- (a)
zero
- (b)
4 \(ms^{-1}\)
- (c)
1 \(ms^{-1}\)
- (d)
2 \(ms^{-1}\)
An object is resting at the bottom of two strings which are inclined at an angle of \(120^{o}\) with each other. Each string can withstand a tension of 20 N. The maximum weight of the object that can be sustained without breaking the string is
- (a)
10 N
- (b)
20 N
- (c)
\(20\sqrt2 N\)
- (d)
40 N
Consider the statements:
A. An astronaut in an orbiting artificial satellite is weightless
B. Both the satellite and the astronaut undergo free fall
C. If the cable that supports the elevator were to break, the elevator would be in free fall
Mark if :
- (a)
A is correct only
- (b)
A, B are correct only
- (c)
A, C are correct only
- (d)
A, B, C are correct
A marble block of mass 2 kg lying on ice when given a velocity of 6 ms-1 is stopped by friction in 10 s. Then, the coefficient of friction is
- (a)
0.02
- (b)
0.03
- (c)
0.06
- (d)
0.01
A bird dismounts on a stretched telegraph wire. The additional tension produced in the wire is:
- (a)
zero
- (b)
greater than the weight of the bird
- (c)
less than the weight of the bird
- (d)
equal to the weight of the bird
A block of mass m is placed on a smooth inclined plane of inclination e with the horizontal. The inclined plane is accelerated horizontally so that the block does not slide down. What is the vertical force exerted by the inclined plane on the block?
- (a)
mg sinθ
- (b)
mg cosθ
- (c)
mg
- (d)
None of these
A rocket of mass 120 kg is fired in the gravity free space. It ejects gases with velocity 600 m s-1 at the rate of 1 kg/s. What will be the initial acceleration of the rocket?
- (a)
1 ms-2
- (b)
5 ms-2
- (c)
10 ms-2
- (d)
15 ms-2
If F1 + F2 + F3 = 0, then;
- (a)
F1>F2
- (b)
F2>F3
- (c)
F3>F1
- (d)
none of these
A jet of liquid of cross-sectional area a strikes a wall making angle 8 with the wall. The water strikes with the wall with velocity v and rebounds elastically. If density of liquid be p, the normal force on the wall is:
- (a)
2 av2 p sin \(\theta\)
- (b)
2av2 p cos \(\theta\)
- (c)
2av p sin \(\theta\)
- (d)
2av p cos \(\theta\)
A body of mass 10 kg falls from a height of 5 m (g = 10m/ s 2 ) and is stopped with in one-tenth of a second on the ground. The force of interaction is:
- (a)
100 N
- (b)
Zero
- (c)
1000 N
- (d)
1100 N
Two masses M1 and M2 are connected to the ends of a string passing over a smooth pulley. The tension in the string is T and the masses are moving with acceleration a. If the masses are interchanged, then:
- (a)
both a and T will change
- (b)
a will change but T will remain unchanged
- (c)
T will change but a will remain unchanged
- (d)
none of them will change
Suppose a rocket with an initial mass M0 expels a mass Δm in the form of gases in time Δt, then the mass of the rocket after time t is:
- (a)
M0
- (b)
M0+\(\frac { \triangle m }{ \triangle t } \)
- (c)
M0-\(\frac { \triangle m }{ \triangle t } \)t
If F denotes force and \(\tau \) denotes torque, then the condition for equilibrium is:
- (a)
\(\sum { F } \neq 0,\sum { \tau } \neq 0\)
- (b)
\(\sum { F } \neq 0,\sum { \tau } =0\)
- (c)
\(\sum { F } =0,\sum { \tau } \neq 0\)
- (d)
\(\sum { F } =0,\sum { \tau } =0\)
A force of 2kg is applied at one end of spring balance kept horizondally and an equal force of 2 kg is applied at the other end in the opposite direction, simltaneously , then the reading on the spring balance is:
- (a)
2 kgf
- (b)
4 kgf
- (c)
0 kgf
- (d)
1 kgf
If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will:
- (a)
go on increasing
- (b)
go on decreasing
- (c)
first increases and then decreases
- (d)
remain the same
To avoid slipping while walking on ice, one should take smaller steps because of the:
- (a)
large friction of ice
- (b)
larger normal reaction
- (c)
small friction of ice
- (d)
smaller normal reaction
If n small balls, each of mass m, impinge elastically each second on a surface with a velocity u, then the force experienced by the surface in one second, will be:
- (a)
0.5 mnu
- (b)
1 mnu
- (c)
2 mnu
- (d)
4 mnu
If μk is the coefficient of kinetic friction, μr the coefficient of rolling friction and μs the coefficient of static friction then generally:
- (a)
μs > μk > μr
- (b)
μs < μk < μr
- (c)
μs < μk > μr
- (d)
μs > μr > μk
The rate of mass of the gas emitted from rear of a rocket is initially 0.1 kg/sec. If the speed of the gas relative to the rocket is 50 m/sec and mass of the rocket is 2 kg, then the acceleration of the rocket (in m/sec2) is:
- (a)
5
- (b)
5.2
- (c)
2.5
- (d)
25
The area under the displacement-force curve gives:
- (a)
distance travelled
- (b)
total force
- (c)
momentum
- (d)
work done
A block slides with a velocity of 10 m/s on a rough horizontal surface. It comes to rest after covering a distance of 50 metres. If g is 10 m/sec2, then the coefficient of dynamic friction between the block and the surface is:
- (a)
0.1
- (b)
1
- (c)
10
- (d)
5
A drum of radius R and mass M rolls down without slipping along an inclined plane of angle θ. The frictional force:
- (a)
dissipates energy as heat
- (b)
decreases the rotational motion
- (c)
decreases the rotational and translational motion
- (d)
converts translational energy to rotational energy
A body is rolling on the ground with a velocity of 1 m/s. After travelling a distance of 5 m, the body stops. The coefficient of friction is:
- (a)
0.00102
- (b)
0.0102
- (c)
0.102
- (d)
1.02
Which of the following is NOT an illustration of Newton's third law?
- (a)
Flight of a jet plane
- (b)
A cricket player lowering his hands while catching a cricket ball
- (c)
Walking on floor
- (d)
Rebounding of a rubber ball
If a ladder weighing 250 N is placed against a smooth vertical wa\I having coefficient of friction between it and floor as 0.3, then what is the maximum force of friction available at the point of contact between the ladder and the floor?
- (a)
75 N
- (b)
50 N
- (c)
35 N
- (d)
25 N
A force of 2 kg is applied at one end of a spring balance kept horizontally and an equal force of 2 kg is applied at the other end in the opposite direction, simultaneously. Then the reading on the spring balance is:
- (a)
2 kgf
- (b)
4 kgf
- (c)
0 kgf
- (d)
1 kgf
A conveyor belt is moving at a constant speed of 2 ms-1. A box is gently dropped on it. The coefficient of friction between them is μ = 0.5. The distance that the box will move relative to belt before coming to rest on it, taking g= 10 ms-2, is:
- (a)
0.4 m
- (b)
1.2 m
- (c)
0.6 m
- (d)
zero
A constant force F acts on a particle of mass 1 kg moving with a velocity v, for one second. The distance moved in that time is:
- (a)
0
- (b)
\(\frac{F}{2}\)
- (c)
2F
- (d)
\(\frac{v}{2}\)
- (e)
v+\(\frac{F}{2}\)
A person is driving a vehicle at uniform speed of 5 ms-1 on a level curved track of radius 5 m. The coefficient of static friction between tyres and road is 0.1. Will the person slip while taking the turn with the same speed? Take g = 10 ms-2.
Choose the correct statement.
- (a)
A person will slip if v2 < 5 m2s-2
- (b)
A person will slip if v2 = 5 m2s-2
- (c)
A person will not slip if v2 > 10 m2s-2
- (d)
A person will slip if v2 > 5 m2s-2