Page 78 - Force 10

Q.7. It is dangerous to jump from significant height.

It takes long time to reach the ground on jumping from significant height.

Increase in time cause to increase the velocity of falling object. As a result,

the body of the falling person strikes the ground with very high retarding

force and experiences serious injury. Since, velocity is directly proportional to

time taken (V ∝ ) and force is directly proportional to velocity of falling

object.

Q.8. Although the Jupiter is 319 times greater than the earth, its acceleration

due to gravity increases only by 2.5 times more than the earth, why?

The Jupiter is 319 times bigger in size than the earth by its mass so that

acceleration due to gravity increases but increase in size equally causes the

radius to increase which cause to decrease the value of acceleration due

to gravity. Since, acceleration due to gravity is directly proportional to mass

of heavenly body and inversely proportional to square of radius of heavenly

body. Hence, if doesn’t increase by 319 times but increases only 2.5 times

than the acceleration due to gravity of the earth.