Question No. 1
a) If the average velocity of the object in the given interval of time is zero then what will be value of its displacement? Explain the reason.
b) Is it possible that an object have weight but no mass? Explain the reason.
Marks = 5+5=10
a) If the average velocity is continuously zero then this is easy to deal with. The object has not moved at all and so its displacement is zero. If it has moved and the average velocity is zero, then this means that at the end of the time interval, the object was back where it started this means the displacement is zero and so the average velocity is zero over the time period.
b) It is not possible. Mass is quantity of matter in the body which remains always same everywhere. Weight is force of gravity which always changes with gravity. At enter of earth gravity is zero so weight is zero but mass of an object will not zero.
Question No. 2 The required speed of a commercial aeroplane is 120 knots before it can take off. If this plane take 30 s to cover the runway then calculate
b) Runway length
[Hint: knot is nautical mile per hour or equal to half a meter per seconds]
Marks =5+5= 10
1 Knot=1/1.944 meter per seconds
1 Knot=0.514 meter per seconds
120 Knot=0.514 ×120 meter per seconds
120 Knot≈61 meter per secondsAcceleration
Vi =0 ms-1
Vf =61 ms-1
Vf =61 ms-1
s=V_i t+1/2 at^2