Question

sports car driver travelling at 95 miles per hour Slams the brakes and comes to rest in 4 seconds calculate the average acceleration of the car in metre per second square​

Answer 1

u=95 miles/hr= 42.46m/s Approx.

v=0

t=4 s

a= -42.46/4

a= -10.61 m/s^2

Answer 2

The average acceleration is -10.6ms⁻²

GIVEN

Initial velocity 95mph

Time taken = 4 sec

TO FIND

Average Acceleration of the car.

SOLUTION:

we can simply solve the above problem as follows-

It is given,

The initial velocity of the car, 'u' = 95 mph

We will first convert 95mph to meter per second

we will convert mph to kilo per hour then to meter per second.

$\frac{95miles}{hour} \times \frac{1.6093km}{1mile} \times \frac{1000meter}{1km} \times \frac{1hr}{60min} \times \frac{1min}{60sec}$

= 42.4 m/s

Now, the body comes to rest

so, the final velocity = 0.

Retardation is negative of acceleration

$a = \frac{v - u}{t}$

where,

u = initial velocity

v = final velocity

acceleration (in this case, retardation)

t = time taken

putting the values in the above equation we have,

$a = \frac{0 - 42.4}{4}$

a = -10.6

Hence, the average acceleration is -10.6ms⁻²

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