Question

A driver is driving his car along a road is shown in Fig. 1.3. The driver makes sure that the speedometer reads exactly 40 km/h. the driver should say that

• A. the average speed is 40 km/h
• B. the average velocity is 40 krn/h
• C. the average speed is 80 krn/h
• D. the average velocity is 80 km/h

Answer 1

The correct option is A the average speed is 40 km/h

speed is magnitude of velocity of the body.

so if speedometer is showing 40 km/h then its speed is constant no doubt may be velocity is changing its direction but between point P and Q direction is also constant so speed as well as velocity both are constant

.but between point Q ans R direction of velocity changes so net final velocity is having some component in downward direction also.

as speedometer shows 40 so speed is always 40 so average speed is 40km/s. but displacement is less then distance covered as direction is changing so average velocity will be less then 40km/s.

so best possible option is A.