Question

A car accelerated from rest to 72km/hr in 5secs given that r=0.25m, find the number of revolution

Answer 1

Answer:

The number of revolution = 31.83

Explanations:

The car starts from rest

The initial velocity, u = 0 m/s

The final velocity, v = 72 km/hr

v = 72 x 1000/3600

v = 20 m/s

The time, t = 5 secs

The radius of the wheel of the car, r = 0.25 m

Find the acceleration using the formula

v = u + at

20 = 0 + 5a

5a = 20

a = 20/5

a = 4 m/s

Find the distance using the formula

s = ut + 0.5at²

s = 0(5) + 0.5(4)(5²)

s = 0 + 50

s = 50m

The number of revolution is calculated using the formula below:

`n\text{ = }(s)/(2\pi r)`
`\begin{gathered} n\text{ = }(50)/(2*3.142*0.25) \\ n\text{ = }31.83 \end{gathered}`

The number of revolution = 31.83