Amisha Singh Solutions for Chapter: Work and Energy, Exercise 1: Exercise

What is the unit of work?

Rashmi was playing on a swing in a park. To increase her speed when her swing was at its lowest position during its oscillations, she pushed the ground hard with her feet. She enjoyed it but could not understand the mechanism. Her elder brother Pankaj explained her the reason when she asked him.
 Why did the swing’s speed increase on pushing the ground harder with feet?
 

Rashmi was playing on a swing in a park. To increase her speed when her swing was at its lowest position during its oscillations, she pushed the ground hard with her feet. She enjoyed it but could not understand the mechanism. Her elder brother Pankaj explained her the reason when she asked him.
Why and what did Rashmi ask Pankaj?

What are the various forms of energy?

A body is thrown vertically upwards. Its velocity goes on decreasing. What happens to its kinetic energy as its velocity becomes zero?

A boy weighing $\mathit{40}\mathit{ }\mathrm{kg}$ makes a high jump of $\mathit{1}\mathit{.}\mathit{5}\mathit{ }\mathrm{m}$. What is his potential energy at the highest point? (Take $g = \mathit{10}\mathit{ }\mathrm{m} {\mathrm{s}}^{-2}$)

A man is instructed to carry a package from the base camp at B to summit A of a hill at a height of $1200 \mathrm{meters}$. The man weighs $\mathit{1000} \mathrm{N}$ and the package weighs $\mathit{200}\mathit{ }\mathrm{N}$. What is the potential energy of the package at A if it is assumed to be zero at B? (Take $g=10 \mathrm{m} {\mathrm{s}}^{-2}$)

A rocket of $\mathit{3}\mathit{ }\mathit{\times }\mathit{ }{\mathit{10}}^{\mathit{6}}\mathit{ }\mathrm{kg}$ mass takes off from a launching pad and acquires a velocity of $1 \mathrm{km} {\mathrm{s}}^{-1}$ at an altitude of $\mathit{25}\mathit{ }\mathrm{km}$. Calculate the kinetic energy.