A particle is free to move along the X -axis has potential energy given by U x = k 1 - e - x 2 for - ∞ ≤ x ≤ + ∞ , where k is a positive constant of appropriate dimensions. Then:

for small displacements from x = 0 , the motion is simple harmonic.

at points away from the origin, the particle is in unstable equilibrium

for any finite non-zero value of x , there is a force directed away from the origin

if its total mechanical energy is k / 2 , it has its minimum kinetic energy at the origin

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A block of mass $m$ is kept on a platform which starts from rest with constant acceleration $\frac{g}{2}$ upward, as shown in figure. Work done by normal reaction on block in time $t$ is :

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Important Questions on Work, Energy and Power

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 24

A particle which is experiencing a force, given by

\vec{F} = 3 \vec{i} - 12 \vec{j},

undergoes a displacement

\vec{d} = 4 \vec{i} .

If the particle had a kinetic energy of

3 J

at the beginning of the displacement, what is its kinetic energy at the end of the displacement?

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 25

The heart of man pumps

5 litres

of blood through the arteries per minute at a pressure of

150 mm of mercury

. If the density of mercury be

13.6 \times 10^{3} kg m^{- 3}

and

g = 10 m s^{- 2}

then the power of heart in watt is ?

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 26

What is the minimum velocity with which a body of mass

m

must enter a vertical loop of radius

R

so that it can complete the loop

?

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 27

A particle of mass

10 g

moves along a circle of radius

6.4 cm

with a constant tangential acceleration. What is the magnitude of this acceleration if the kinetic energy of the particle becomes equal to

8 \times 10^{- 4} J

by the end of the second revolution after the beginning of the motion ?

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 28

Two particles of masses

m_{1}, m_{2}

move with initial velocities

u_{1}

and

u_{2} .

On collision, one of the particles get excited to the higher level, after absorbing energy

ϵ

. If the final velocities of particles be

v_{1}

and

v_{2}

, then we must have

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-3>Q 29

A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy

K

with time

t

most appropriately? The figures are only illustrative and not to the scale.

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-4>Q 1

A body is executing simple harmonic motion. At a displacement

x

, its potential energy is

E_{1}

and at a displacement

y

, its potential energy is

E_{2}

. The potential energy

E

at a displacement

(x + y)

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Alpha Question Bank for Medical: Physics>Chapter 8 - Work, Energy and Power>Exercise-4>Q 2

A particle is free to move along the $X$ -axis has potential energy given by $U (x) = k [1 - e^{- x^{2}}]$ for $- \infty \leq x \leq + \infty$ , where $k$ is a positive constant of appropriate dimensions. Then:

A block of mass m is kept on a platform which starts from rest with constant acceleration g2 upward, as shown in figure. Work done by normal reaction on block in time t is :

Important Questions on Work, Energy and Power

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A block of mass $m$ is kept on a platform which starts from rest with constant acceleration $\frac{g}{2}$ upward, as shown in figure. Work done by normal reaction on block in time $t$ is :