Work

Find the equivalent value of $1 \mathrm{J}$ in its CGS units.

$1 \mathrm{J}=1\times {10}^4 \mathrm{erg}$.

What is the relation between SI unit of work and CGS unit of work?

When a spring is _____, work done by the force is positive.

(Choose from: compressed/stretched)

The amount of work done by the centripetal force when the earth revolves around the sun is _____.

(Choose from zero/non-zero)

Force of $4 \mathrm{N}$ is applied on a body of mass $20 \mathrm{kg}$. Find the work done in Joules in $3$rd second.

A man spends $6.4 \mathrm{k} \mathrm{J}$ energy in displacing a body by$64 \mathrm{m}$ in the direction in which he applies force, in $2.5 \mathrm{s}$. The force applied and the power spent (in hp) by the man respectively are:

An electric motor of power $100 \mathrm{W}$ is used to drive the stirrer in a water bath. If $50\%$ of the energy supplied to the motor is spent in stirring the water, calculate the work done (in joules) on water in one minute.

Force acting opposite to the direction of motion of a body does negative work on it.

The power of heart which beats $72$ times in a minute is $1.2 \mathrm{kW}$. Calculate the work done (in joules) by the heart for each heartbeat.

Force and displacement are inclined to each other at an angle of $120°$. Will the work done be positive or negative?

A man pulls a bucket out of a well by means of a rope. The work done by the man is

The work done by a force is _____ (positive/ negative/ zero) if the displacement in the direction of the force increases.

A body is displaced by $10 \mathrm{m}$ when maximum work of $200 \mathrm{J}$ is done on it. Calculate the force acting on this body in newton.

A body constrained to move along y-axis is subjected to a constant force $\overrightarrow{F}=-\widehat{i}+2\widehat{j}+3\widehat{k} \mathrm{N}.$ The work done by this force in moving the body a distance of $4 \mathrm{m}$ along $Y$-axis is _____ $\mathrm{J}$.

When a spring is pulled up to $0.02 \mathrm{m}$ then work done is $0.4 \mathrm{J}$. Find the spring constant.

An object displaces $10 \mathrm{m}$ when $20 \mathrm{N}$ force is applied on it. Calculate the work done.

A man carrying a load on his head and moving along a horizontal road does _____ work.
(Choose from: zero/positive/negative)

Force and displacement are inclined to each other at an angle of $120°$. Will the work done be positive or negative?

A particle of mass $0.5 \mathrm{kg}$ is displaced from position $\overrightarrow{r_1}\mathrm{ }(2,\mathrm{ }3,\mathrm{ }1)$ to $\overrightarrow{r_2}(4,\mathrm{ }3,\mathrm{ }2)$ by applying a force of magnitude $30 \mathrm{N}$ which is acting along $\left(\widehat{\mathrm{i}}+\widehat{\mathrm{j}}+\widehat{\mathrm{k}}\right)$ . The work done by the force is