The speed- time graph of a car is given in (figure) The car weights `1000kg`
(a) What is the distance travelled by the car in first two seconds?
(b) What is the braking force applied at the end of `5 seconds` to bring the car to a stop within one second?

Explanation

Here mass of car m=1000kg
distance s=?
In the first two seconds the speed time graph is OA.
s= area of `Delta OAE`
`=(base times height)/2= (OE times EA)/2`
`s=(2 times 15)/2=15m`
(ii) Initial speed `u=15 ms^-1`
final speed v=0
time taken t=1s
braking force F=?
As `F=ma=(m(v-u))/t, F=(100(0-15))/1`
`F=-15000N`
Negative sign is for opposing force.