Physics - Newton's Laws of Motion
Exam Duration: 45 Mins Total Questions : 30
A force F varies simultaneously with time. The average force is ( \(F_{o} \) is peak value of force )
- (a)
\(F_{o} \)
- (b)
\(F_{o} \)\(/\pi\)
- (c)
zero
- (d)
\(2F_{o} \)
A black slides with a velocity of 10\(ms^{-1}\) on a rough horizontal surface. It comes to rest after covering a distance of 50 m. If g is 10 \(ms^{-2}\), then coefficient of dynamic friction between the block and surface is
- (a)
1
- (b)
10
- (c)
0.2
- (d)
0.1
Two skaters A and B of mass 50 kg, stand facing each other, 6m apart on a horizontal smooth surface. They pull a rope stretched between them.
How far has each moved when they meet ?
- (a)
Both have moved 3 m
- (b)
A moves 4 m and B moves 2m
- (c)
A moves 2.5 m and B moves 3.5 m
- (d)
A moves 3.5 m andB moves 2.5 m
Two cars of masses m1 and m2 are moving in circles of radii r1 and r2, respectively. Their speeds are such that they make complete circle in the same time t. The ratio of their centripetal acceleration is
- (a)
\({ m }_{ 1 }{ r }_{ 1 }:{ m }_{ 2 }{ r }_{ 2 }\)
- (b)
\({ m }_{ 1 }:{ m }_{ 2 }\)
- (c)
\({ r }_{ 1 }:{ r }_{ 2 }\)
- (d)
\(1:1\)
A rocket with a lift - off mass \(3.5\times { 10 }^{ 4 }\) kg is blasted upwards with an initial acceleration of 10 ms-2. Then the initial thrust of the blast is
- (a)
\(3.5\times { 10 }^{ 5 }N\)
- (b)
\(7.0\times { 10 }^{ 5 }N\)
- (c)
\(14.0\times { 10 }^{ 5 }N\)
- (d)
\(1.75\times { 10 }^{ 5 }N\)
If an inclined plane is made slowly horizondal by reducing its inclination with horizondal , the componet of weight parallel to the plane of block resting on the inclined plane:
- (a)
remains same
- (b)
increases
- (c)
decreases
- (d)
first increases and then decreases
Two bodies A and B have masses M and m respectively, where M > m and they are at a distance d apart. Equal force is applied to them so that they approach each other. The position where they hit each other is:
- (a)
nearer to B
- (b)
nearer to A
- (c)
at equal distance from A and B
- (d)
cannot be decided
Three forces are acting on a particle of mass m initially in equilibrium. If the first 2 forces (R1 and R2) are perpendicular to each other and suddenly the third force (R3) is removed, then the acceleration of the particle is:
- (a)
\(\frac { { R }_{ 3 } }{ m } \)
- (b)
\(\frac { { R }_{ 1 }+{ R }_{ 2 } }{ m } \)
- (c)
\(\frac { { R }_{ 1 }-{ R }_{ 2 } }{ m } \)
- (d)
\(\frac { { R }_{ 1 } }{ m } \)
A force of 20 N is applied on a body of mass 5 kg resting on a horizontal plane. The body gains a kinetic energy of 10 joule after it moves a distance 2 m. The frictional force is:
- (a)
10 N
- (b)
15N
- (c)
20 N
- (d)
30 N
A body slides down the inclined plane of inclination θ. The coefficient of friction (μ) varies in direct proportion to the distance covered on the inclined plane. What happens to the downward acceleration of the body?
- (a)
It is equal to (g sinθ - μg cosθ)
- (b)
It is equal to (μg sinθ - g cosθ)
- (c)
It increases with time
- (d)
It decreases to zero with time and then its direction is reversed
A body is moving with uniform velocity of 2 ms-1 on a rough level surface. The frictional force on it is 10 N. If the body moves with velocity 4 ms-1 the force of friction will be:
- (a)
2.5 N
- (b)
5 N
- (c)
10 N
- (d)
20 N
A piece of ice slides down a 45° incline in twice the time it takes to slide down a frictionless 45° incline. What is the coefficient of friction between the ice and incline?
- (a)
0.25
- (b)
0.50
- (c)
0.75
- (d)
0.40
A box of mass 50 kg is pulled up on an inclined plane of 12m long and 2 m high by a constant force of 100 N from rest. It acquires a velocity of 2 m/s when it reaches the top of the plane. The work done against friction (in joule) is: (g = 10 m/s2)
- (a)
50
- (b)
100
- (c)
150
- (d)
200
A body takes 1\(\frac{1}{3}\) times as much time to slide down a rough inclined plane as it takes to slide down an identical but smooth inclined plane. If the angle of inclined plane is 45°, the coefficient of friction is:
- (a)
\(\frac{7}{16}\)
- (b)
\(\frac{9}{16}\)
- (c)
\(\frac{7}{9}\)
- (d)
\(\frac{3}{4}\)
A suitcase is gently dropped on a conveyor belt moving at 3 m/s. If the coefficient of friction between the belt and the suitcase is 0.5, find the displacement of the suitcase relative to conveyor belt before the slipping between the two is stopped: (g = 10m/s2)
- (a)
2.7 m
- (b)
1.8 m
- (c)
0.9 m
- (d)
1.2 m
A spring balance and a physical balance are kept in a lift. In these balances equal masses are placed. lf now the lift starts moving upwards with constant acceleration, then:
- (a)
the reading of spring balance will increase and the equilibrium position of the physical balance will disturb
- (b)
the reading of spring balance wilI remain unchanged and physical balance will remain in equilibrium
- (c)
the reading of spring balance will decrease and physical balance wi\I remain in equilibrium
- (d)
the reading of spring balance will increase and 'he physical balance wi\I remain in equilibrium
A body of mass 10 kg is moving with a constant velocity of 10 m/s. When a constant force acts for 4 s on it, it moves with a velocity 2 m/s in the opposite direction. The acceleration produced in it is:
- (a)
3 m/s2
- (b)
-3 m/s2
- (c)
0.3 m/s2
- (d)
-0.3 m/s2
A large force is acting on a body for a short time. The impulse imparted is equal to the change in:
- (a)
acceleration
- (b)
momentum
- (c)
energy
- (d)
velocity
- (e)
displacement
1654060945.png)
1654060942.png)
1653987551.png)
1653987086.png)
1582095229.jpg)
