PHYSICS [2 Mark Question Answer]

In velocity-time graph a straight line shows body is moving with uniform constant velocity if it is parallel to x axis and shows body is moving constant acceleration of it is inclined to x axis.

In displacement-time graph a straight line shows body is at rest if it is parallel to time axis and shows a body is moving with uniform velocity if it is inclined to x axis.

36 km/ hr can be converted into m/ s to compare with 8.5m/ s.
36 km/ hr = {36 x 1000) / 3600 = 10 m/ s which is greater than
8.5 m/ s So 36 km/ hr is greater than 8.5 m/ s.

60 km/hr can be converted into m/s to compare with 15m/s.
60 km/hr = (60 X 1000)/3600 = 16.66 m/s. so speed 60 km/hr is greater.

speed time graph for a non uniform acceleration.

Speed time graph for a stepped motion

If speed time graph is moving upward then the body is accelerating and if it is starting from origin then it means the body has initial velocity =0.

As we distance = speed X time.
Speed = 42 km/hr.
Time = 10 m = 1/6 hr.
Distance = 42 X 1/6 =7 km.

A straight line curve on speed time graph indicates that acceleration of the body is uniform and a zigzag or curved line indicates that acceleration of a body is not uniform.

(i) Motion of blades of an electric fan.
(ii) Motion of moon around earth.

A uniformly accelerated motion is one in which speed is constantly increasing or decreasing with time while a non uniform motion is one in which speed is not constantly changing with time.

When the velocity of a moving body doesn't change with time then the velocity of the body is said to be constant or uniform.Yes uniform velocity and constant velocity are one and the same thing.

Speed is a scalar quantity whereas velocity is a vector quantity. So speed doesn't have its direction and velocity has a particular direction.

As body goes from P to Q and then return back to P so the displacement of the body would be zero and hence average velocity would also be zero.

If a book is lying in almirah then it is at rest.

Total displacement =0 as starting and ending points are coinciding.

Total dist ance travelled = dist ance from A to B +distance from B to A
So total distance = H +H = 2H.

Distance is 2+2+2+2+2+2=12m while displacement is 2+2+2=6m.

Distance is 2+4+2+4=12m while displacement is 0m.

Distance is 4+4=8 m while displacement is 3m.

(i) Distance is a scalar quantity whereas displacement is a vector quantity.
(ii) Distance is always positive but displacement can be negative,zero or positive.

In this case Distance travelled = half of the parameter of circle.
So distacne travelled is = πr
Displacement = diameter of circle.
So displacement is 2r

The actual length of the path covered by a moving object irrespective of its direction of motion is called the distance travelled by the object.

Yes we are at rest as well as motion because we are at rest with respect to a observer which is itself at rest and we are in motion with respect to a observer which is in motion.