Question

a car increase its speed from 20km/h to 50 km/h in 10 seconds. Its acceleration is

(a) 30m/s^2
(b) 3m/s^2
(c) 18 m/s ²
(d) 0.83m/s^2​

Answer 1

Given-

Final velocity, v = 50 km/h

Initial velocity, u = 20 km/h

Time taken, t = 10 sec

So the change in velocity can be calculated as

v−u=(50−20)km/hr

= 30 km/hr

On converting the units into m/s

We get,

= 30 km/hr ⇒30×100060×60⇒253 m/s

We know the acceleration formula,

a=(v−u)t

Put the value of change in velocity and time in above formula

we get,

=253×110

=56 m/s2

There is no such option.

So the correct answer is option D (none)

Additional Information: Velocity of the body increases with time then acceleration formed and if the velocity of the body decreases then retardation formed

So we say that negative acceleration is called retardation

If a body moving with a constant velocity therefore change in velocity is zero . Then the acceleration is also zero.