Work, Power and Energy

Question 1

Work Done

Answer 1

Scalar product of force and displacement

Question 2

Work-Energy Theorem

Answer 2

Work done by all the forces on a body is equal to change in kinetic energy of the body

Question 3

Extension of a spring in equilibrium(xo)

Answer 3

xo = mg/k

Question 4

Maximum Extension

Answer 4

x = 2mg/k

Question 5

Keff of the series combination

Answer 5

1/keff = 1/k1 + 1/k2
Tension same in the series combination

Question 6

Keff of the parallel combination

Answer 6

Keff = k1+k2
Elongation is same in the parallel combination

Question 7

Uniform Circular Motion

Answer 7

Speed remains same, while the velocity changes at every point
Acceleration: Centripetal Acceleration

Question 8

Non-uniform circular motion

Answer 8

Speed does not remain constant, velocity changes
Acceleration: Centripetal and Tangential Acceleration

Question 9

Angular Velocity

Answer 9

Rate at which angular displacement changes

Question 10

Relation between w and v.

Answer 10

v = wR

Question 11

Time taken in a pendulum

Answer 11

t = 2pi root(l/g), where l is the length of the pendulum

Question 12

For circular turning of roads when only friction is applied, what is the vmax?

Answer 12

vmax = root(Rμg), where μs = coefficient of static friction

Question 13

For circular turning of roads when only banking is applied, what is the vmax?

Answer 13

vmax = root(Rgtanθ), where θ is the angle by which the road is banked

Question 14

For circular turning of roads when friction and banking is applied, what is the vmax?

Answer 14

v = root{Rgtan(θ+α)}, where tanα =μs, where μs = coefficient of static friction

Question 15

Velocity of one point w.r.t to another point in a vertical circular motion

Answer 15

vp = va^2 - 2gr(1-cosθ)

Question 16

Minimum velocity conditions on vertical circular motion

Answer 16

Tension should not be zero at any point except for the top-most point