Law of Conservation of Energy

Q. What are the factors affecting the density of a body?

Q.

A sphere of radius$‘a’$ and mass $‘m’$ rolls along horizontal plane with constant speed$v_0$. It encounters an inclined plane at angle $\theta$ and climbs upward. Assuming that it rolls without slipping how far up the sphere will travel (along the incline)?

1. $\frac{2}{5}\hspace{0.17em}\left(\frac{v_0^2}{g\sin \theta }\right)$

2. $10\left(\frac{v_0^2}{7g\sin \theta }\right)$

3. $\frac{v_0^2}{5g\sin \theta }$

4. $7\left(\frac{v_0^2}{10g\sin \theta }\right)$

Q. When we rub our hands, they get warm because mechanical energy gets converted into energy.

1. heat
2. electrical
3. wind

Q.

$kg{m}^2{s}^{-2}$ is the unit of

1. Force

2. Energy

3. Power

4. momemtum

Q.

The sum of potential and kinetic energy is known as total mechanical energy.

1. True

2. False

Q.

S.I unit of kinetic energy is joule(J).What is the S.I unit of potential energy?

Q. The sum of the potential and kinetic energy of a body is called energy.

1. electrical
2. mechanical
3. heat

Q. a body is projected at an angle 60^° with the horizontal ground with kinetic energy K. When the velocity makes an angle 30^° with the horizontal , the horizontal , the kinetic energy of the body will be

Q. Why do telephone wires sag in summer?

Q. If a simple pendulum of length l and mass m has maximum angular displacement , then find its maximum kinetic energy.

Q. A block of mass 10 kg is moving on a rough surface with velocity 4m/s in opposite direction of 20N force. Given coefficient of kinetic friction is (0.6 )Then find frictional force in block .

Q. An object is dropped from a height h from the ground .every time it hits the ground it loses 50percent of its kinetic energy.the total distance covered is

Q.

A steel ball of mass $5g$ is thrown downward with a velocity of $10m{s}^{-1}$ from a height of $19.5m$ and it penetrates sand by $50cm$. The change in mechanical energy will be (take, $g=10m{s}^{-2}$ )

1. $1J$

2. $1.25J$

3. $1.5J$

4. $1.75J$

Q. Energy changes from one form to another form, but total energy ______ .

1. alternates
2. increases
3. decreases
4. remains constant

Q.

A spring gun of spring constant $90Nc{m}^{-1}$ is compressed $12cm$ by a ball of mass $16g$. If the trigger is pulled, the velocity of the ball is

1. $50m{s}^{-1}$

2. $9m{s}^{-1}$

3. $40m{s}^{-1}$

4. $60m{s}^{-1}$

5. $90m{s}^{-1}$

Q. The figure shows a swinging pendulum, the kinetic energy of the pendulum is maximum at:

1. B
2. C
3. A, C
4. A

Q. Where would this basketball tossed upward have the least amount of kinetic energy?

1. Point X
2. Point W
3. Point Y
4. Point Z

Q.

An unstretched rubber band has potential energy.

1. 1 KJ

2. -1 KJ

Q.

It is the energy due to motion

1. Chemical energy

2. Potential energy

3. Kinetic energy

4. Electrical energy

Q. The crane in the figure shown utilizes ________ energy?

1. magnetic
2. chemical
3. heat
4. sound

Q.

The power delivered to a projectile by gravity force at the highest point of the trajectory is

1. non zero

2. zero

3. Positive

4. can’t say anything

Q.

What kind of energy is possessed by the following?

A stretched rubber band.

Q.

What is the potential and kinetic energy formula?

Q.

If a body is dropped from certain height, Kinetic enegy is maximum when the body is at top most position.

1. True

2. False

Q.

When an apple falls freely from the tree towards the ground, then its total mechanical energy _________.

1. increases

2. decreases

3. first increases and then decreases

4. remains constant

Q.

A moving train has complete mechanical energy in the form of potential energy.

1. True

2. False

Q.

Which of the following energy conversions is depicted in the figure given below?

1. Kinetic energy of the spring is converted into potential energy of the ball.

2. Kinetic energy of the ball is converted into potential energy of the spring.

3. Potential energy of the spring is converted into kinetic energy of the ball.

4. Potential energy of the ball is converted into kinetic energy of the spring.

Q.

Explain the energy transformation taking place in a freely falling body.

Q.

The law of conservation of energy states that the energy can be created, but cannot be destroyed.

1. True

2. False

Q. Match the following in which the electrical energy is converted in to different forms of energy:-

1. Sound energy
2. Mechanical energy
3. Magnetic energy
4. Heat energy