Question

a car starts from rest and accelerates at a uniform rate of 5 metre per second square for 20 seconds then it travels with a uniform speed for another 10 second then the brakes are applied so that car comes to rest after 5 seconds calculate the total distance travelled by the car​

Answer 1

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Answer 2

Answer:

1st part(acceleration):

u=0. a=5 m/s². t=20 s

s = ut+½at² = 0 + ½*5*400 = 1000 m

v = u + at = 0 + 100 = 100 m/s²

2nd part:

u= 100 m/s. t = 10 s. a=0

s = ut+½at² = 100*10 + 0. = 1000 m

3rd part (deceleration):

u=100m/s t = 5 s. v = 0

a = (v-u)/t = -20 m/s²

s = ut-½at²(as it is deceleration)

or, s = 500 - ½*(-20)*25

or, s = 750 m

So, total distance travelled is 1000 + 1000 + 750 m = 2750 m