Potential energy

Q.

A bullet of mass $10g$ is fired horizontally with a velocity $1000m{s}^{-1}$ from a rifle situated at a height $50m$ above the ground. If the bullet reaches the ground with a velocity$500m{s}^{-1}$, the work done against air resistance in the trajectory of the bullet is (take $g=10m^{-2}$).

1. $5005J$

2. $3755J$

3. $3750J$

4. $17.5J$

Q.

Find the rate of doing work by a man of 60 kg in climbing a staircase of vertical height of 10 m in half a minute. Take, g = 10 m/s².

Q.

Give an example of an object with potential energy.

Q.

Potential energy of your body is minimum when___________.

1. you are standing on the ground

2. you are sitting on the ground

3. you lie down on the ground

4. you are sitting on a chair kept on the ground

Q.

The mechanical energy of a moving train is only in the form of its potential energy.

1. True

2. False

Q.

Which of the following statement is true regarding the hydropower plant?

1. Water is converted into steam to produce electricity.

2. The potential energy possessed by the stored water is converted into electricity.

3. Kinetic energy possessed by the stored water is converted into potential energy.

4. Electricity is extracted from the chemical energy possessed by water.

Q. In hydrogen atom if potential energy of first exited state is taken as reference zero potential then total energy of ground state will be 6.8eV -6.8eV 13.6eV -13.6eV

Q.

A body of mass 5 kg is thrown vertically upwards so that it reaches a maximum height of 50 m in 20 seconds. Find the work done.

1. $2500J$

2. $1250J$

3. $3500J$

4. $500J$

Q.

Two paths lead to the top of a hill. Path I is shorter and steeper and path II is longer but less steep. For which of the two paths is the gain in potential energy more?

1. Path I

2. Path II

3. Same for both the paths

4. None of the above

Q. The energy possessed by a body by virtue of its height is called .

1. kinetic energy
2. potential energy
3. heat energy

Q.

Define mechanical energy.

Q. Gravitational potential energy is possessed by an object due to its position above the ground.

1. True
2. False

Q.

A person of mass $50kg$runs up to the staircase of $40$ steps in $6sec$. If the height of each step is $15cm$, then his power will be (If $g=10m/s^2$)

1. $300W$

2. $500W$

3. $600W$

4. $1000W$

Q.

Expression of potential energy is given by?

1. $\frac{mg}{h}$

2. $\frac{h}{mg}$

3. $mgh$

4. $mgv$

Q. What does the negative sign indicate in the formulae of Gravitational potential energy ?explain.

Q. The energy possessed by a body by virtue of its height is called .

1. kinetic energy
2. potential energy
3. heat energy

Q. Gravitational potential energy is possessed by an object due to its position above the ground.

1. True
2. False

Q.

What happens to the potential energy of an object, if its mass is doubled and its lifted height is halved from its initial state?

1. Becomes quadruple

2. Becomes double

3. Becomes half

4. Remains same

Q. Calculate the potential energy of a stone weighing 2.5 kg placed at a height of 6m

Q.

Potential energy is independent of:

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

Q.

Rahul takes 1 minute to raise a box to a height of 1 metre and Rohan takes $\frac{1}{2}$ minute for the same work. Comment on the energy consumed by the two in doing so.

1. Energy spent by both Rahul and Rohan is same.

2. Energy spent by the Rohan is more

3. Data insufficient

4. Energy spent by the Rahul is more.

Q. The sum of potential energy and kinetic energy is always a constant.

1. False
2. True

Q. 500 litres of water is raised from the first floor of a house at height 4 m to its third floor at height 12 m. If density of water is $1kg{l}^{-1}$ then the change in potential energy is (take $g=10m{s}^{-2}$):

1. $4\times {10}^{4}J$
2. $-4\times {10}^{4}J$
3. $2\times {10}^{4}J$
4. $-2\times {10}^{4}J$

Q.

When a lift is going up, the potential energy of the person with respect to earth inside a lift remains the same.

1. True

2. False

Q.

What happens to the potential energy of an object, if its mass is doubled and its lifted height is halved from its initial state?

1. Becomes quadruple

2. Remains same

3. Becomes double

4. Becomes half

Q.

Potential energy depends on:

1. change in position of the object

2. velocity with which the object moves

3. mass of the object

4. time required to move the object

Q.

What happens to the potential energy of an object, if its mass is doubled and its lifted height is halved from its initial state?

1. Becomes quadruple

2. Becomes double

3. Becomes half

4. Remains same