Question

The velocity-time graph (v-t) of a car moving along a
level road is shown below. The average speed of the
car in the time interval 0 to 8 s is about???

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Answer 1

Answer:

4.48 m/s

Explanation:

Velocity at t = 0 is 10 m/s

Velocity at t = 5 sec is -5 m/s

Acceleration = (-5 -10)/(5 - 0)

= - 3 m/s²

Distance covered till Speed becomes 0

using V² - U² = 2aS

=> S = (0² - 10²)/(2(-3))

=> S = 50/3 m

Distance covered from 0 velocity to - 5

= 5²/2(-3)

= 25/6  m (in opposite direction)

From 5 to 8 Sec

Distance covered = -5 * 3

= 15 m ( in opposite direction)

Total Distance Covered

= 50/3  + 25/6  + 15

= 215/6 m

Time = 8 sec

Average Speed = (215/6)/8  = 4.48 m/s

Average Velocity =  (50/3  - 25/6  - 15)/8 = - 15/48  = -0.3125 m/s

Answer 2

Answer:

4.48 m/sec is the answer