A stone falls freely under gravity. It covers distances h1 , h2 and h3 in the first 5 seconds, the next 5 seconds and the next 5 seconds respectively. The relations between h1, h2 and h3 is,
h1 = 2 h2 = 3 h3
h1 =
h2 = 3 h1 and h3 = 3 h2
h2 = 3 h1 and h3 = 3 h2
B.
h1 =
Relations between h1, h2 and h3 is,
A particle is moving such that its position coordinates (x,y) are (2m, 3m) at time t = 0, (6m, 7m) at time t = 2 sec and (13 m, 14m) at time t= 5 sec. Average velocity vector (vav) from t = 0 to t = 5 s is,
D.
Average velocity vector,
A ship A is moving Westwards with a speed of 10 kmh-1 and a ship B 100km south of A, is moving Northwards with a speed of 10 kmh-1. The time after which the distance between them becomes shortest is
0 h
5 h
B.
5 h
It is clear from the diagram that the shortest distance between the ship A and B is PQ.
The motion of a particle along a straight line is described by equation
x=8+12 t -t3
where x is in metre and t in second. The retardation of the particle when its velocity becomes zero, is
24 ms-2
zero
6 ms-2
6 ms-2
D.
6 ms-2
Given : x=8+12 t -t3
The force F acting on a particle of mass m is indicated by the force-time graph as shown below. The climate change in momentum of the particle over the time interval from zero to 8 s is,
24 Ns
20 Ns
12 Ns
12 Ns
C.
12 Ns
The area under F-t graph gives change in momentum.
For 0 to 2 s,
For 2 to 4 sec,
For 4 to 8 sec,
So, total change in momentum for 0 to 8 sec is,