Question

A racing car, initially at rest. Pick up a velocity of 180 km/hr in 4.5 m/s. Calculate (a) acceleration
(b) distance covered by car

Answer 1

a) We know that,

Acceleration is the rate of change of velocity.

Therefore,

A = V/t

Putting the values of V and t, we get,

A = 180*18/5 / 4.5 (I multiplied the velocity by 18/5 to change km/h to m/s, It's a quick and easy shortcut)

A = 144 m/s

b) The question is unclear.

You need the time taken to calculate the distance traversed.

In a) , you have given the time as m/s, which is wrong unit for time. It should be in seconds.

Hope it helped!

Answer 2

u (initial velocity) of the car = 0m/s

v (final velocity) of the car = 180km/h

(since the final velocity is given in km/h we will convert it into m/s by multipling it by 1000/60)

                                                    =180000m/s

time taken = 4.5m/s

(a) acceleration of the body

we know that acceleration = v-u/t

                                              = 180000-0/4.5

                                              =40,000m/s(sq)

(b) distance travelled by the car

since distance is denoted by `s'

we will find the answer by the formulae

s=ut + 1/2 x at(sq)

s=0 x 4.5 + 40000 x 4.5 x 4.5. 0.5 ( half)

 = 0+405000m

  = 405000/1000

   = 405 km

ANS: (a)40000 (b) 405 km