Potential Energy

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Find the gravitational potential energy of a 1 kg mass kept at a height of 5 m above the ground. Calculate its kinetic energy when it falls and hits the ground. (take g=10 m/s²)

Q.

Give two examples of potential energy?

Q.

A cricket ball of mass $0.15kg$ is thrown vertically up by a bowling machine so that it rises to a maximum height of $20m$ after leaving the machine. If the part pushing the ball applies a constant force$F$ on the ball and moves horizontally a distance of $0.2m$ while launching the ball, the value of $F$ is ($g=10m{s}^{–2}$)

Q.

State law of resistance "in series" and "in parallel". How will you connect various resistances to increase and decrease it?

Q.

An object of mass $12kg$ is at a certain height above the ground. If the potential energy of the object is $4800J$, find the height at which the object is with respect to the ground. (Given $g=10m{s}^{-2}$)

Q.

Define the term potential energy of a body. Name its two forms and give one example of each.

Q.

Name the form of energy which a wound up watch spring possesses.

Q.

A car is accelerated on a leveled road and attains a velocity$4times$of its initial velocity. In this process the potential energy of the car

1. Does not change

2. Becomes twice to that of initial

3. Becomes 4 times that of initial

4. Becomes 16 times that of initial

Q.

State the energy changes taking place when the water stored in the dam produces electric current on passing through electric generator.

1. Kinetic energy → Electrical energy → Potential energy

2. Potential energy → Kinetic energy → Electrical energy

3. Potential energy → Electrical energy → Kinetic energy

4. Electrical energy → Kinetic energy → Potential energy

Q.

In the SI system, the unit of P.E. is

1. erg

2. dyne-cm

3. joule

4. none of these

Q.

Potential energy is independent of:

1. Path taken by the object.
2. Mass of the object.
3. Position of the object.
4. Shape of the object.

Q.

Coal and oil have _______ energy stored in them.

Q.

A ball, when kept on a spring attains a certain height after it is compressed and released. For which of the following height attained by the ball, maximum of his energy is required to compress the spring?

1. $3m$
2. $5m$
3. $9m$
4. $7m$

Q.

A mass of 3kg is thrown vertically upwards with a kinetic energy of 600J. To what height will it rise? (g = 10ms^–2).

1. 20 m

2. 60 m

3. 23 m

4. 27 m

Q. A 0.5 kg ball is thrown up with an initial speed 14m per sec. And reaches a max. Height of 8 m. How much energy is dissipated by air drag acting on the ball during the ascent?

Q.

Can potential energy change into kinetic energy only? (directly )

Q.

What kind of energy is possessed when an arrow held in a stretched bow.

Q.

What is energy? Explain conservation of energy with an example. [3 MARKS]

Q.

Q. An object is at a height of 2 m, and another object is at a height of 5m. Which of them have higher potential energy?
PS: It’s not about the height!

Q.

A ball of mass 0.20 kg is thrown vertically upwards with an initial velocity of 20 m s^-1 Calculate the maximum potential energy it gains as it goes up.

1. 2 J

2. 4 J

3. 20 J

4. 40 J

Q.

Give two examples of (a) bodies possessing gravitational P.E. (b) bodies possessing elastic P.E.

Q. Two boys $\text{A}$ and $\text{B}$ are standing at two positions on a staircase. $\text{B}$ has a $500\text{g}$ ball in his hand which is $50\text{cm}$ higher than the platform he is on. Each step is $20\text{cm}$ high and $20\text{cm}$ wide.

$\text{B}$ drops the ball from his hand down the stairs and $\text{A}$ stops the ball on the second step. Find the change in potential energy of the ball.


Consider $\text{g}$ $=10{\text{m s}}^{-2}$ and assume that there is no loss of energy when the ball rolls down the staircase.

1. $+8.5\text{J}$
2. $+6.0\text{J}$
3. $-6.0\text{J}$
4. $-8.5\text{J}$

Q.

Question 20
Three 2 ~$\Omega$ resistors, A, B and C, are connected as shown in the figure. Each of them dissipates energy and can withstand a maximum power of 18 W without melting. Find the maximum current that can flow through the three resistors?

Q. A ball is projected vertically upwards with a certain initial speed. Another ball of the same mass is projected at an angle of sixty degree with vertical with same initial speed. At highest point of their journey what will be ratio of their potential energies?

Q. Water stored in a dam has energy, while water flowing in a river has energy.

1. potential
2. kinetic
3. tidal
4. thermal

Q.

Define the potential energy of an object.

Q.

Burning of fossil fuels changes chemical energy to the muscular energy.

1. True
2. False

Q.

The relationship between the SI and CGS unit of work.

1. 1 J = 10⁵ erg

2. 1 J = 10⁸ erg

3. 1 J = 10⁷ erg

4. 1 J = 10 erg

Q. How is the unit horse power related to the S.I. unit of power?

Q. A ball of mass 500 grams is suspended with the help of a light, inextensible string of length 100 cm. The maximum value of to which the string rotates from the mean position A to reach the extreme position C is ${60}^{\circ }$. Consider $g=10m/s^2$

i. What will be the potential energy of the ball when it reaches half the maximum height from position A?

[1 mark]

1. P.E. = 2.25 J
2. P.E. = 0.5 J
3. P.E. = 1.25 J
4. P.E. = 0.75 J