Tag: physics

Questions Related to physics

Potential energy is classified into which two energy?

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

  1. Gravitational and Elastic Potential Energy

  2. Kinetic and Elastic Potential Energy

  3. Mechanical and Elastic Potential Energy

  4. None

Show answer
Correct Option: A
Explanation:

Gravitational and Elastic Potential Energy are two types of potential energy

Gravitational potential energy: Energy stored in the object at a certain height above ground.
Elastic potential energy:Energy stored in streched or compressed spring.

Mechanical energy is the form of which two energies:

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

  1. Potential and Kinetic

  2. Thermal and Nuclear

  3. Potential and Sound

  4. Light and Sound

Show answer
Correct Option: A
Explanation:

Mechanical energy comprises of Potential and Kinetic energy.

Which one of the following is NOT a form of energy?

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

  1. Mechanical energy

  2. Nuclear Energy

  3. Thermal Energy

  4. Leap Energy

Show answer
Correct Option: D
Explanation:

Leap energy is not any kind of energy

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

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

  1. Kinetic energy

  2. Potential energy

  3. Mechanical energy

  4. Both kinetic and mechanical energies.

Show answer
Correct Option: A
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.

Identify, which of the following energies can be positive only

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

  1. kinetic energy

  2. potential energy

  3. mechanical energy

  4. both kinetic and mechanical energies

Show answer
Correct Option: A
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.

What kind of energy transformation takes place

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

  1. When an arrow is shot its bow

  2. running water

  3. Moving plane

  4. A stretched spring

Show answer
Correct Option: A
Explanation:

The kind of energy transformation takes place

When an arrow is short its bow

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

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

  1. $12\ m$

  2. $15\ m$

  3. $18\ m$

  4. $16\ m$

Show answer
Correct Option: A

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?

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

  1. $I$ and $II$ only

  2. $I$ and $III$ only

  3. $III$ only

  4. $II$ and $III$ only

Show answer
Correct Option: D
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

Energy required to break a bond of DNA is approximately

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

  1. ~ 1 eV

  2. ~ 0.1 eV

  3. ~ 0.01 eV

  4. ~ 2.1 eV

Show answer
Correct Option: A
Explanation:

The bond energy of a DNA molecule is 1 eV, so this will be the energy required to break the bond

A system absorbs 600 J of energy and does work equivalent to 400 J of energy. The internal energy change is

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

  1. 1000 J

  2. 200 J

  3. 600 J

  4. 300 J

Show answer
Correct Option: B
Explanation:

$\begin{array}{l} We\, \, know\, \, that, \ \Delta E=Q+W \ =600+\left( { -400 } \right)  \ =200J \end{array}$

Hence,
Option $B$ is correct.