Question

A force of 10N acts for 20sec on a body of mass 2kg initially at rest.Calculate the energy required by the body and the work done by the applied force

Answer 1

Answer :

It is 10,000 Joules (OR) 10 Kilo. joules

Explanation:

Given :

- Force acting( F ) = 10 Newtons

- Time taken ( t ) = 20 Seconds

- Mass of body( m ) = 2 Kg

- Initial Velocity ( u ) = 0 { Since, at rest. }

------------------------------------------------------------------

Now,

according to 1st equation of motion :

-> V = u + at

-> V = 0 + at

-> a = V/t ------------------point 1.

according to Newton's 1st law :

-> F = ma

-> 10 = 2 (V/t)

-> 10 = 2 ( V/20)

on simplifying above equation, we will get

-> V = 100 m/sec.

Finally now,

Energy required by body = Work done is

$(1 \div 2) \times m \times {v}^{2}$

so now

-> 1/2 x 2 x (100 x 100)

-> 10,000 Joules

-> 10 Kilo. Joules.

Answer 2

Answer:

It is 10,000 Joules (OR) 10 Kilo. joules

Explanation:

Given :

- Force acting( F ) = 10 Newtons

- Time taken ( t ) = 20 Seconds

- Mass of body( m ) = 2 Kg

- Initial Velocity ( u ) = 0 { Since, at rest. }

------------------------------------------------------------------

Now,

according to 1st equation of motion :

-> V = u + at

-> V = 0 + at

-> a = V/t ------------------point 1.

according to Newton's 1st law :

-> F = ma

-> 10 = 2 (V/t)

-> 10 = 2 ( V/20)

on simplifying above equation, we will get

-> V = 100 m/sec.

Finally now,

Energy required by body = Work done is

(1 \div 2) \times m \times {v}^{2}(1÷2)×m×v

2

so now

-> 1/2 x 2 x (100 x 100)

-> 10,000 Joules

-> 10 Kilo. Joules.