Question

 A car , starting from rest attains a velocity of 60 km/hr in 10 seconds. It's acceleration will be-
a. 3/5 m/s square
b. 5/3 m/s square
c. 2/5 m/s square
d. Zero​

Answer 1

Given:-

→Initial velocity of the car = 0

(as the car was initially at rest)

→Final velocity of the car = 60km/h

→Time taken = 10s

To find:-

→Acceleration of the car

Solution:-

Firstly, let's convert the final velocity of the car from km/h to m/s.

=>1km/h = 5/18m/s

=>60km/h = 5/18×60

=>50/3 m/s

Hence, we have got the final velocity of the car as 50/3 m/s.

By using the 1st equation of motion, we get:-

=>v = u+at

=>a = v-u/t

=>a = (50/3-0)/10

=>a = (50/3)/10

=>a = 50/30

=>a = 5/3 m/s²

Thus, acceleration of the car is

5/3 m/s² (Option.b)

Some Extra Information:-

The three equations of motion for a body moving with uniform acceleration are:-

•v = u+at

•s = ut+1/2at²

•v² - u² = 2as

Answer 2

Given :-

☄ Initial velocity, u = 0

☄ Final velocity, v = 60km/h

☄ Time taken, t = 10s

To find:-

Acceleration of the car

Conversion :-

1km/h = 5/18m/s

60km/h = 5/18×60 = 50/3 m/s

Solution :-

By using the 1st equation of motion, .i.e.,

$\leadsto \bf v = u+at \\ \\ \leadsto \sf \dfrac{50}{3} = 0 + (a)(10) \\ \\ </p><p>\leadsto \sf a = \dfrac{\dfrac{50}{3} - 0}{10} \\ \\ </p><p>\leadsto \sf a = \dfrac{ \dfrac{50}{3} }{10} \\ \\ </p><p>\leadsto \sf a = \dfrac{50}{30} \\ \\ </p><p>\leadsto \sf a = \dfrac{5}{3} m/s² \\ </p><p>$

Thus, acceleration of the car is option (b) 5/3m/s² .