Question

A sprinter goes off the starting block for $100$ m run and at that instant the second-hand of a stopwatch had pointed towards North. He touches the finishing line exactly after $12$ seconds. In which direction did the second hand point when he just crossed the finishing line?

• A. ${18}^o$ North of East
• B. ${18}^o$ East of North
• C. ${72}^o$ North of East
• D. ${82}^o$ East of North

Answer 1

The correct option is A ${18}^o$ North of East

In a stopwatch,

15 seconds would make ${90}^o$

so 12 seconds would make $\frac{90\times 12}{15}={72}^o$ in clockwise direction with the North

This is same as $90-72$ = ${18}^o$ in anti-clockwise direction with the East.

Which is same as ${18}^o$ North of East

option A