Average Speed and Velocity

Question 1:

A car moves from X to Y with a uniform speed \[v_{u}\] and returns to X with a uniform speed \[v_{d}\]. The average speed for this round trip is

1. \[\frac{2v_{d}v_{u}}{v_{d}+v_{u}}\]

2. \[\sqrt{v_{d}v_{u}}\]

3. \[\frac{v_{d}v_{u}}{v_{d}+v_{u}}\]

4. \[\frac{v_{u}+v_{d}}{2}\]

View Answer

\[ \frac{2}{V_{av}}= \frac{1}{V_{1}}+\frac{1}{V_{2}} \]

Question 2:

A cyclist moving on a circular track of radius 40 m completes half a revolution in 40 s. Its average velocity is :

1. zero

2. \[4\pi ms^{-1}\]

3. \[2 ms^{-1}\]

4. \[8\pi ms^{-1}\]

View Answer

Displacement = 2R = 80 m

Time = 4o sec

Velocity= 80 m/ 40 sec = 2 m/s

Question 3:

A car moves a distance of 200 m. It covers first half of the distance at speed 60 kmh–¹ and the second half at speed v. If the average speed is 40 kmh–¹, the value of v is

1. 30 kmh–¹

2. 13 kmh–¹

3. 20 kmh–¹

4. 40 kmh–¹

View Answer

Vav = 30 m / s