Work Done in Different Frames of Reference

Q.

Which of the following is not correct for the condition for work not to be done:

1. force and displacement are at 180 degrees with each other

2. displacement is zero, though force is non-zero

3. force is zero

4. force and displacement are perpendicular to each other.

Q. A block of mass $10\text{kg}$ pulled by force $100\text{N}$. It covers a distance $500\text{m}$ in $10s$. From initial point this motion is observed by two observers $A$ and $B$ as shown in fig.



Find out work done by force $F$ in 10 seconds w.r.t. $A$ and $B$ respectively.

1. $5000\text{J}$ and $5000\text{J}$
2. $5000\text{J}$ and $0$
3. $4000\text{J}$ and $0$
4. $0$ and $6000\text{J}$