A block of mass m is in contact with the cart C as shown in the figure


The coefficient of static friction between the block and the cart is μ. The acceleration α of the cart that will prevent the block from falling satisfies

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C.

When a cart moves with some acceleration toward right then a pseudo force (mα) acts on block towards left. The force (mα) is action force by a block on the cart. Now, block will remain static w.r.t cart if frictional force 

A circular disk of moment of inertia I_t is rotating in a horizontal plane, about its symmetry axis, with a constant angular speed. Another disk of moment of inertia I_b is dropped coaxially onto the rotating disk. Initially, the second disk has zero angular speed. Eventually, both the disks rotate with constant angular speed.The energy lost by the initially rotating disc due to friction is 

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D.

Loss of energy, 

The radii of circular orbits of two satellites A and B of the earth are 4R and R, respectively. If the speed of satellite A is 3v. then the speed of satellite B will be

• 3v/4

• 6v

• 12 v

• 3v/2

A ball is dropped from  a high-rise platform at t=0 starting from rest. After 6s another ball is thrown downwards from the same platform with a speed v. The two balls meet at t= 18s. What is the value of v? (take g= 10 ms^-2)

• 74 ms^-2

• 55 ms^-1

• 40 ms^-1

• 60 ms^-1

A.

74 ms^-2

A ball moving with velocity 2 ms^-1 collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5, then their velocities (in ms^-1) after collision will be

• 0,1

• 1,1

• 1,0.5

• 0,2