Physicspoint Quiz Time

Q1. Two blocks of mass 10 kg each is kept on a horizontal surface with one block sitting on the other.What minimum force should be applied on the upper block so that both the blocks accelerate? The coefficient of fricton is 0.4 between all the surfaces.

• 80 N

• 120 N

• 40 N

• 180 N

Q2. A ball thrown horizontally gains velocity after it hits the ground. In which of the following situation this can happen?

• Th ball gains kinetic energy from the ground

• The ball is rotating initialy. After hitting the ground its kintic energy of rotation changes to kinetic energy of translation

• It gains momentum from ground

• It starts to spin after it hits the ground.

Q3. A chain of length 1 m and of mass 1 kg is on a table with a part hanging out from the edge. What should be the minimum length of the chain that should hang out so that the chain starts to slide down. Coefficient of friction=1/4.

• 0.2 m

• 0.66 m

• 0.55 m

• 0.75 m

Q4. (continued from Q3) Find the velocity of the chain when it completely falls off from the edge of the table.

• 2.5 m/s

• 2.2 m/s

• 2.82 m/s

• 2 m/s

Q5. A plank of length 1 m rests on a horizontal surface. A block of mass 1 kg is placed on the plank at the centre. A torque is appled on one end of the plank so that the plank and the mass rotates on the other edge with angular acceleration of 1 rad/s². Find the resultant force acting on the block when the plank makes 20^o with the horizontal.

• At the center

• exactly at the opposite end

• at the same point directed upwards

• none of these

Q6. A cubical block of mass 100 kg and with side 1 m is moved through a distance of 1 m by turning it on its edge. What is the minimum work required to do this?

• 1.0J

• 1.5J

• 2.0J

• 3.0J

Q7. A ramp of mass M rests on smooth frictionless surface, the ramp surface making angle a with the horizontal. A block of mass m is placed on the ramp. There is no friction between the block and the ramp. Find the accleration of the ramp when the block is sliding down the ramp?

• [m/M] cos a sin a

• [m/M]

• [M/m] cos a sin a

• None of these

Q8. An uniform beam of mass m, and length l rests on a horizontal surface. Find the work required to rotate the beam through 90^o about an axis through its center of mass, by applying a couple on its ends. Coefficienet of friction is u.

• (pi)umgl/24

• (pi)umg L²

• (pi)umgl/16

• (pi)umgl/8

Q9.Two bodies of equal mass moving with velocities 2 m/s in the opposite direction collide. After the collision If the velocity of one body is 1.8 m/s what can be said about the velocity of the other body?

• It will be less than 1.8 m/s

• equal to 1.8 m/s

• more than 1.8 m/s

• cannot be said definitely

Q10 A block is to be dragged on a horizontal surface by a rope attached to the block. If the coefficient of friction bbetween the block and the surface is m, at what angle to the horizontal, the dragging force will be minimum.

• at 45^o

• tan^-1 m

• tan m

• can not be found