11.

Assertion: In javelin throw, the athlete throws the projectile at an angle slightly more than 45^o.

Reason: The maximum range does not depend upon the angle of projection.

• If both assertion and reason are true and reason is the correct explanation of assertion. 

• If both assertion and reason are true and reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false

Assertion:  The apparent weight of a body in an elevator moving with some downward acceleration is less than the actual weight of a body.

Reason:  The part of the weight is spent in producing downward acceleration, when body
is in elevator.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion:  A horse has to pull a cart harder during the first few steps of his motion. 

Reason: The first few steps are always difficult.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

Assertion: A wheel moving down a perfectly frictionless inclined plane will undergo slipping (not rolling motion) 

Reason:  For perfect rolling motion, work done against friction is zero.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion:  A hollow shaft is found to be stronger than a solid shaft made of same material. 

Reason:  The torque required to produce a given twist in hollow cylinder is greater than that required to twist a solid cylinder of same size and material.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion: If momentum of a body increase by 50%, its kinetic energy will increase by 125 %.

Result: Kinetic energy is proportional to square of velocity.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion:  The difference in the value of acceleration due to gravity at pole and equator is proportional to square of angular velocity of earth. 

Reason:  The value of acceleration due to gravity is minimum at the equator and maximum at the pole.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Two masses  M₁ = 5 kg  and  M₂ =  10 kg  are  connected at the ends of an inextensible string  passing  over  a frictionless  pulley  as  shown. When  the  masses  are  released, then  the  acceleration  of  the  masses  will  be

• g

• g/2

• g/3

• g/4

A uniform string is vibrating with a fundamental frequency  ' f ' . The new frequency, if radius & length both are doubled would be

•  2f

• 3f

• $\frac{\mathrm{f}}{4}$

• $\frac{\mathrm{f}}{3}$

Two spherical soap bubbles of radii a and b in vacuum coaleasce under isothermal conditions. The resulting bubbles has a radius given by

• $\frac{\left(\mathrm{a} + \mathrm{b}\right)}{2}$

• $\frac{\mathrm{ab}}{\mathrm{a} + \mathrm{b}}$

• $\sqrt{{\mathrm{a}}^2 + {\mathrm{b}}^2}$

• a+ b