Tag: forms of energy and energy conservation

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Questions Related to forms of energy and energy conservation

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

Identify, which of the following energies can be positive only:

  1. Kinetic energy

  2. Potential energy

  3. Mechanical energy

  4. Both kinetic and mechanical energies.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Potential energy is the energy stored by the virtue of the position of a body.While,kinetic energy is the energy possessed by the virtue of motion.
Hence, K.E is always +ve .
When a body is raised to a particular height,work is done against the force of gravity and P.E is $ - $ve.
When the body is falling freely the work is done in the direction of force of gravity and P.E is $+$ ve.

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

Identify, which of the following energies can be positive only

  1. kinetic energy

  2. potential energy

  3. mechanical energy

  4. both kinetic and mechanical energies
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Only kinetic energy can have positive value. Potential energy has negative value and mechanical energy is combination of these two hence can either be positive or negative.

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

A ball is dropped from $30\ m$ on hitting the ground if it loses $40$% of its energy, it rebounds to a height equal to

  1. $12\ m$
  2. $15\ m$
  3. $18\ m$
  4. $16\ m$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The initial potential energy of the ball is proportional to 30 m. Since it loses 40% of its energy upon hitting the ground, it retains 60% of its energy. The rebound height will therefore be 60% of the initial drop height, which is 0.60 * 30 = 18 meters.

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

A small sphere is moving at a constant speed in a vertical circle. Below is a list of quantities that could be used to describe some aspect of the motion of the sphere.
$I$   -kinetic energy
$II$  -gravitational potential energy
$III$  - momentum
Which of these quantities will change as this sphere moves around the circle?

  1. $I$ and $II$ only
  2. $I$ and $III$ only
  3. $III$ only
  4. $II$ and $III$ only
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Speed is given as constant. Though the velocity is changing only in direction, its magnitude remains the same. Thus the kinetic energy remains constant as it is a scalar quantity but momentum would change as it is a vector quantity.
Also as the elevation of the ball keeps on changing during the motion, the potential energy changes

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

Raindrops fall on earth with certain kinetic energy on the earth. From where do they get this energy ?

  1. Chemical energy

  2. Gravitational Potential energy

  3. Energy between molecules of water

  4. Heat energy
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

As raindrops fall, they lose gravitational potential energy, which is converted into kinetic energy (ignoring air resistance for this conceptual question).

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

Water stored in a dam primarily possesses

  1. Heat energy

  2. Electrical energy

  3. Kinetic energy

  4. Potential energy
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Answer is D.

Potential energy is the energy that is stored in an object due to its position relative to some zero position. An object possesses gravitational potential energy if it is positioned at a height above (or below) the zero height.
There is potential energy stored in a water reservoir behind a dam. It is converted to kinetic energy when the water starts flowing down the penstock, from the dam. This kinetic energy is used to turn a turbine.
Hence, the water stored in a dam possesses potential energy.