Question

The equation of motion of a car is s=t^2 - 2t, where t is measured in hours and s in kilometers. when the
distance travelled by the car is 15 km, the velocity of the car is
(a) 2km/h
(b) 4km/h
(c) 6km/h
(d) 8km/h​

Answer 1

Answer:

d. 8km/h

Step-by-step explanation:

s=t^2-2t

When distance is 15km,

15=t^2-2t

t^2-2t-15=0

(t-5)(t+3)=0

t=5hrs

Now, v=ds/dt

v=d/dt(t^2-2t)

v=2t-2

At t=5hrs,

v=(2*5)-2=8km/h

Cheers!