Question

According to work energy theorem, work done by net force in displacing a body is always equal to

change in kinetic energy of the body. Similarly, if some work is drawn from the body, kinetic energy of

the body decreases by the same amount. In either process, we assume that potential energy of the body

does not change.

Read the above passage and answer the following questions:

(i) A car weighing 500 kg is running at a speed of 72 km/h. In how much distance will it stop by applying

a braking force of 4000 N?

(a) 20 m

(b) 25 m

(c) 30 m

(d) 40 m

(ii) What is the cgs unit of kinetic energy?

(a) eV

(b) Calorie

(c) Ergs

(d) Joule

(iii) Which of the law is applicable to justify the above principle given in the passage?

(a) Law of conservation of energy

(b) Law of conservation of mass

(c) Law of conservation of momentum

(d) Law of conservation of angular momentum

(iv) What is the change in kinetic energy of a baseball hit with a force of 6000 N that travels 120 m

across the field?

(a) 6000 J

(b) 240 J

(c) 120000 J (d) 720000 J

(v) Which of the following factors are related by work energy theorem given in above passage?

(a) force, displacement and time

(b) force, velocity, time and mass

(c) force, velocity and displacement

(d) displacement, time and mass​

Answer 1

Answer:

According to work energy theorem or work energy principle, work done by net force in displacing a body is always equal to change in K.E. of the body. ... The theorem implies that under ideal conditions, our achievement / output will be equal to work put in by us.