問PHY 1999 CE MC Q.1 AND Q.7

1. Total distance

= AB + BC

= 120 + 100

= 220 m

Total time

= 30 + 20

= 50 s

So, average speed

= total distance / total time

= 220 / 50

= 4.4 m/s


So, the answer is D.



7. By s = ut + 1/2 at^2

s = (0)(4) + 1/2 (3)(4)^2

s = 24 m

So, force acting on the car

= ma

= 2000 X 3

= 6000 N

So, useful power

= work done / time

= Fs / t

= 6000 X 24 / 4

= 36 kW

So, the answer is B.