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: 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

A force F acting on an object varies with distance x as shown in the figure. The force is in N and x in m. The work done by the force in moving the object from x = 0 to  x  = 6 m is

• 13.5 J

• 10 J

• 15 J

• 20 J

84.

A body is moved along a straight line by a machine delivering constant power. The distance travelled by the body in  time t is proportional to

• t^1/2

• t

• t^3/2

• t²

P, Q and R are three coplanar forces acting at a point and are in equilibrium. Given: P = 1.9318 kg wt [sin θ₁ = 0.9659], the value of R (in kg wt) is

• 0.9659

• 2

• 1

• 1/2

If a solid sphere of mass 1 kg and radius 0.1 m rolls without slipping at a uniform velocity of I m/s along a straight line on a horizontal floor, the kinetic energy is

• $\frac{7}{5}$ J

• $\frac{2}{5}$ J

• $\frac{7}{10}$ J

• 1 J

The voltage of clouds is 4 x 10 volt with respect to ground. In a lightening strike lasting 100 msec, a charge of 4 coulombs is delivered to the ground. The power of the lightning strike is

• 160 MW

• 80 MW

• 20 MW

• 500 MW

For inelastic collision between two spherical rigid bodies

• the total kinetic energy is conserved

• the total potential energy is conserved

• the linear momentum is not conserved

• the linear momentum is conserved

A person used force (F), shown in figure to move a load with constant velocity on surface. Identify the correct surface profile.

A block of mass 10 kg is moving in x-direction with a constant speed of 10 m/sec. It is subjected to a retarding force F = -0.1 x joule/meter during its travel from x = 20 meter to x = 30 meter. Its final kinetic energy will be

• 475 joule

• 450 joule

• 275 joule

• 250 joule