Question

Q] Choose one option and explain how it is correct
1) Which of the following is a vector?
a) The height of a boy is 92 cm.
b) The radius of the earth is approximately 4000 km.          
c) Height of tree is 5 m
d) The office of GBSTA is 50 m to the west of Malad Station. 

2) When a ball strikes stump on what factor does the intensity of the strike depend?
a) Only on the mass of the ball.         b) Only on the velocity of the ball.
c) Both on the mass and velocity of the ball.          d) On the mass of the stumps.

3) Which of the following is not the illustration of negative acceleration?
a) A ball hit by a batsman stops on the boundary.    b) A stone thrown upwards in the sky.
c) A fruit falling from the tree.                          d) A train arriving at the station

Answer 1

1. some thing is a vector if it follows law of vector addition (parallelogram
     law of vectors)

a)  Height  -  No  because  height of one person + height of another person = not
     equal to height a third person. it does not make sense.  magnitude specified in
     question. direction is not given.
b). Radius is not vector - adding two radius in horizontal & vertical direction we
     should get resultant radius = √2 * radius at 45 degrees, if radius is a vector.
     radius is equal in all directions - like pressure.  only magnitude specified and
       not direction.
c) height of tree - same as above. only magnitude specified.
d) the position of GBSTA from malad station, is: 50m in magnitude and direction to
   the west from Malad stn - YES. here magnitude n direction r specified.

2 ) c ) depends on momentum - mass * velocity of ball. this is called IMPACT.

3) c) fruit falling is case of uniform acceleration towards the surface of earth -
     vertically downwards.