Second Law of Motion

Q.

Three uniform spheres of mass M and radius R each are kept in such a way that each touches the other two. The magnitude of the gravitational force on any of the spheres due to the other two is

1. 

2. 

3. 

4. 

Q.

A man weighing 80 kg is standing in a trolley weighing 320 kg. The trolley is resting on frictionless horizontal rails. If the man starts walking on the trolley with a speed of 1 m / s, then after 4 sec his displacement relative to the ground will be

1. 5 m

2. 4.8 m

3. 3.2 m

4. 3.0 m

Q. A car moving towards north at a speed of 10m/s turns right within 10s maintaining the same speed. Average acceleration of the car during this time interval is

Q. 69.In a capillary tube experiment, a vertical 30 cm long capillary tube is dipped in water. The water rises upto a height of 10 cm due to capillary action. If this experiment is conducted in a freely falling elevator, the length of water column becomes

Q. What is the formula for instantaneous acceleration?

Q.

A stone is dropped from the top of a tower. If it travels 34.3m in the last second before it reaches the ground, find the height of the tower? Take g=10m/$s^2$

Q. 47.An object is dropped from the top of a tower. It travels a distance x in the first second of its motion and a distance 7x in last second. Height of the tower is 1) 40m 2) 45m 3) 75m 4) 80m

Q. A force gives an object of m1 an acceleration of12 m/s2 and an object of mass m2, an accelerationof 10 m/s2. The ratio of accelerations the force would give to an object of mass m2- m1 and m2 +m

Q. a body is thrown horizontally from a tower 100m high at t=0with a velocity 10m/s .The velocity of the body is directed at an angle 45degree with the horizontal at a time equ al to

Q. a stone projected up with velociyt u reaches a maximum height h. When it is at a height of 3h/4 from the ground, the ratio of kE and PE at that point i

Q. 40.What is the minimum coefficient of friction for a solid sphere to roll without slipping on an inclined plane of inclination θ ?

Q. A light spring of length 20 cm and force cons†an t 2 N/cm is placed vertically on a table. A small block of mass 1 kg falls on it. The length h from the surface of the table at which the block will have maximum velocity is :_______________

Q. A thin wire of length l and mass m is bent in the form of a semi circle as shown . Its moment of inertia about an axis joining its free ends will be

Q. 19.A particle is projected at an angle 45 . The relation between range and maximum height attained by the particle is:

Q.

The force required just to move a body up an inclined plane is double the force required just to prevent the body sliding down. If the coefficient of friction is 0.25, the angle of inclination of the plane is

1. 36.8°

2. 45°

3. 30°

4. 42.6°

Q. 52. When a 4 kg rifle is fired, the 10 g bullet receives an acceleration of 3000000cm/s^2 The magnitude of force acting on the rifle is 1)0 N 2)120 N 3)300 N 4)3000 N

Q. A flywheel of mass 25 kg has a radius of 0.2m.It is making 240 rpm.What is the torque required to bring it to rest in 20s?If the torque is due to a force applied †an gentially on the rim of the flywheel, what is the force

Q.

A soccer ball is kicked from the ground with an initial speed of 20 m/s at an upward angle of ${45}^{\circ }$. A player 55 m away in the direction of the kick starts running to meet the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground?

1. (4 - 5) m/s

2. (6 - 7) m/s

3. (3 - 4) m/s

4. (5 - 6) m/s

Q. a body is acted upon by balanced forces 1).if it is in rest only 2). if it is moving with cons†an t speed 3). if it is not accelerating. why option (2). is incorrect

Q. Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (a) just after it is dropped from the window of a stationary train, (b) just after it is dropped from the window of a train running at a constant velocity of 36 km/h, (c ) just after it is dropped from the window of a train accelerating with 1 m s-2, (d) lying on the floor of a train which is accelerating with 1 m s-2, the stone being at rest relative to the train. Neglect air resistance throughout

Q.

A truck of mass $M$ is moved under a force $F$. If the truck is then loaded with an object equal to the mass of the truck and the driving force is halved, then how does the acceleration change?

Q. 3.The moment of inertia of the plate in fig(a) about the axis shown is I. The moment of inertia of the hexagonal plate of the same material shown in figure(b) about the axis given in the figure (b) is

Q.

A block of mass 3 kg in contact with a second block of mass 2 kg rests on a horizontal frictionless surface . A horizontal force of 10 N is applied to push the first block. The force with which the first block pushes the second block is:

1. 4 N

2. 6 N

3. 10 N

4. 8 N

Q. 70.A stone is projected vertically up from ground with a velocity 40 m/s. The interval of time between the two instants at which the stone is at height of 60 m above the ground is (g=10 m/s²)

Q. 43.Rain is falling at angle of 37 with vertical with v-10 m/s. Find speed of man with which he should run so that rain appears to falling vertically downward.

Q. A torque of 15 Nm is applied on a body for 1/3 second . The magnitude of change in angular momentum will be

Q.

There are some passengers inside a stationary railway compartment. The centre of masses of the compartment itself(without the passengers) is C1, while the centre of mass of the compartment plus passengers' system is C2. if the passengers moves about inside the compartment

1. both C1 and C2 will move with respect to the ground

2. C1 will move but C2 will be stationary with respect to the ground.

3. neither C1 nor C2 will move with respect to the ground

4. C2 will move but C1 will be stationary with respect to the ground.

Q. Q. An object of mass 80 kg moving with velocity 2metre per second hit by collides with another object of masss 20 kg moving with velocity 4 metre per second . Find the loss of energy assuming a perfectly inelastic collision.

Q.

A lift is moving down with the acceleration 3 m/s². A ball is released 1.7 m above the the lift floor. How long will it take to hit the lift floor.

1. 1.7 s

2. 0.71 s

3. 7.1 s

4. 0.5 s

Q.

Figure shows two blocks in contact sliding down an inclined surface ofinclination 30${}^{\circ }$. The friction coefficient between the block of mass 2.0 kg and the incline is $\mu$${}_1$, and that between the block of mass 4.0 kg and the incline is $\mu$${}_2$. Calculate the acceleration of the 2.0 kg block if (a) $\mu$${}_1$ = 0.20 and $\mu$${}_2$ = 0.30, (b) $\mu$${}_1$ = 0.30 and $\mu$${}_2$ = 0.20. Take g = 10 m/s${}^2$.

1. 2.7 , 1.2

2. 2..3 , 2.4

3. None of these

4. 5.7 , 1.2