Question

The force of 10 N acts on a body of mass 2 kg for a distance of lm. The Kinetic Energy acquired by
the body is
a) 5 J
b) 10J
c) 20J
d) 4.9 J​

Answer 1

RequirEd Solution:

Correct question: The force of 10 N acts on a body of mass 2 kg for a distance of 1 m. The Kinetic Energy acquired by the body is ………

Options for help:

• 5J, 10J, 20J and 4.9J

Given that:

• Body's mass = 2 kilograms

• Force acts on body = 10 Newton's

• Displacement or distance = 1 metre

To find:

• The Kinetic Energy acquired by the body

Solution:

• The Kinetic Energy acquired by the body = 10 Joules

Using concept:

~ As according to the question force of 10 N acts on a body of mass 2 kg for a distance of 1 metres. There is none work shown here. Just there is a force here. That's why

• Kinetic energy = Force × Distance/Displacement

Putting the values we get:

=> Kinetic energy = Force × Distance/Displacement

=> Kinetic energy = 10 × 1

=> Kinetic energy = 10 Joules

♛ Work - If a body get displaced when a force acts on it, work it said to be done. Work is measured by the product of force and displacement of the body along the direction of force. If a body get displaced by S when a force F act's on it, then the work W = ${\sf{FS \: cos \theta}}$

[Where, ∅ denotes angle between force and displacement]

If both force and displacement are in the same direction, then W = FS.

Work is a scaler quantity and it's SI unit is joules.

♛ Energy = Capacity of doing work by a body is called it's energy. Energy is a scaler quantity & it's SI unit is ${\sf{joule}}$ Energy developed in a body due to work done on it is called mechanical energy. Mechanical energy is of two types-

• Potential energy
• Kinetic energy

➜ Potential energy = The capacity of doing work developed in a body due to it's position or configuration is known as potential energy like, ⑴ energy of stretched or compressed string ⑵ energy of spring in a watch ⑶ energy of water collected at a height.

PE of a body is the gravitational field of earth is ${\sf{mgh}}$

(Where, m denotes mass , g denotes acceleration due to gravity and h denotes height of the body from the surface of the earth)

➜ Kinetic energy = Energy posses by a body due to it's motion is called kinetic energy of the body. If a body of mass is moving with speed then kinetic energy of body is ${\sf{\dfrac{1}{2}mv^{2}}}$

(Where, m denotes mass and v denotes speed)

Relation between kinetic energy and momentum-

${\sf{K.E \: = \: \dfrac{p^{2}}{2m}}}$