Question

An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?

Answer 1

Hi ,there !!!


here is your answer :-

the inital and final points lie on the same horizontal line so the net displacement is zero .

so work done is zero .

because work done = > force × displacement ( 0 )


so work done is zero .


hope it helps you !!

thanks !!
Ranjan kumar

Answer 2

●When an object is thrown at a certain angle, it rises to a certain height and then comes back while moving in a parabolic path. Let h be the maximum height to which it rises. As it rises, its kinetic energy decreases but its potential energy increases. Potential energy gained by it in rising to the highest point = work done against gravity. = - mg x h = -mgh   As the body falls down, it gains kinetic energy = work done by the force due to gravity. mg x h = mgh •Net work done by the force due to gravity = - mgh + mgh = 0   •••••••••••••••••••••••••••••••••••••••••••••• (ii) Here, m = 20 kg, u = 5 m s^-1, v = 2 m s^-1 According to work energy principle work done by a force = change in kinetic energy. = 1/2 mv^2 - 1/2 mu^2 = 1/2 x 20 x (2)^2 - 1/2 x 20 x (5)^2 = 40 - 250 = - 210 J