Q : 1.


A person is hanging from the roof of a room as shown in figure.

(a) The man will exert 600 N force on the roof.

(b) The roof exert 600 N force on man.

(c) The force on each arm due to roof is 600 N.

(d) As roof exert 1200 N force on man, so man should accelerate upward.

Answer Option : (C)

Answer Explanation :



Q : 2.


(a) Normal reaction on the each leg of the boy is 200 N .

(b) Normal reaction on the each leg is zero.

(c) Normal reaction on the each leg is 400 N at it will be in equilibrium (Means the position shown in the figure will not change with time).

(d) He can not stay in the position shown.

Answer Option : (D)

Answer Explanation :



=> In the horizontal direction it has two forces -

=> N sin 60 (towards left) and N sin 60 (towards right)

=> Practically you can observe that due to these two forces his legs will come closer. It means that he can not stay in this position shown in the figure.

Q : 3.


If the wire of the lift breaks -

(a) The weight of block will become zero.

(b) The acceleration of block become (10+5) = 15 m/sec² .

(c) Normal reaction on the block will decrease.

(d) Weight of the lift will decrease.

Answer Option : (C)

Answer Explanation :


Weight = Gravitational force = mg .
Acceleration of block = g (Free fall ).
Weight of lift = Gravitational force = mg (Not change).

Normal reaction will become zero, as it was non zero before breaking the wire, it means normal reaction will decrease.

Q : 4.


A man is hanging with a rope (light) passing through a frictionless and mass pulley with a mass of 80 kg as shown in the figure.

(a) He can not lift the mass.

(b) The vertical displacement of man and block will be same in same time, if he is able to pull the block.

(c) The distance x will decrease, if he is just able to pull the block.

(d) The distance x will increase, if he is just able to pull the block.

Answer Option : (D)

Answer Explanation :


To pull the block man has to pull the rope with at least 80 N force.

In this case --

F.B.D. - 




As both are moving upwards, the distance singlequotexsinglequote will increase.

Q : 5.


(a) The acceleration of 2 kg block and 4 kg is same.

(b) Tension in the rope (light) is 4g/3 N.

(c) |Acceleration| of 4 kg block is double the |acceleration| of 2 kg block.

(d) Force on pulley A is 8g/3 N.

Answer Option : (B)

Answer Explanation :



=> Force on pulley A -




Q : 6.


(a) Tension in the rope when lift is in free fall is zero.

(b) The force on block will be along the plane when seen from the lift frame.

(c) Normal reaction will be zero from earth frame but non zero from lift frame.

(d) From lift frame , so block is at rest according to lift frame.

Answer Option : (A)

Answer Explanation :


In this condition its total weight is acting to give it acceleration singlequotegsinglequote in the downward direction.

=> So it will not press the wedge and it will not pull the rope.


Q : 7. In villages, villagers use pulley to pull the water from the well.

(a) With the help of pulley they use less effort to pull more weight.

(b) They use the pulley only for their safety and convenience.

(c) If they use pulley they will feel that their weight is increased.

(d) If they pull the water directly they feel that their weight is decreased.

Answer Option : (B)

Answer Explanation :


F.B.D.

=> So normal reaction will decrease. so he will feel less weight.

=> Tension in the rope is same, so his effort is equal to mg .

F.B.D without pulley


So normal reaction will increase and he will feel more weight.

Q : 8.


In the given diagram a block is at highest point and train is accelerated as shown length of wedge (along inclined) is l = 0.25m.

(a) The block will not slip if .

(b) For every value of a block will slip.
(c) Time taken by block to reach the bottom of wedge will be 1 sec if  .
(d) If we reverse the direction of acceleration of train, block will slip for every value of .

Answer Option : (A), (C) and (D)

Answer Explanation :


=> If  , the block will not slip relative to wedge.

=> , so that block does not slip.
=> Now you can check option (3) and (4) as well.

Q : 9.


(a) The blocks will separate after some time.

(b) They will move together (with contact).

(c) Their acceleration will be more than .

(d) Their acceleration will be less than .

Answer Option : (B)

Answer Explanation : => Their acceleration is same ( ) , so they will move together.

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