Force F on a particle moving in a straight line varies with distance d as shown in the figure. The work done on the particle during its displacement of 12 m is
21 J
26 J
13 J
13 J
C.
13 J
Work done = Area under (F - x) graph
= 2 x (7-3) +
A planet moving along an elliptical orbit is closer to the sun at a distance r1 and farthest away at a distance of r2. if v1 and v2 are the linear velocities at these points respectively, then the ratio v1/v2 is
r2/r1
(r2/r1)2
r1 /r2
r1 /r2
A.
r2/r1
From the law of conservation of angular momentum
mr1v1 = mr2v2
r1v1 = r2v2
v1/v2 = r2/r1
A person of mass 62 kg is inside of a lift of mass 940 kg and presses the button on control panel. The lift starts moving upwards with an acceleration 1.0 m/s2. If g = 10 m/s2 ,the tension in the supporting cable is
9680 N
11000 N
1200 N
1200 N
B.
11000 N
An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of 12 m/s and the second part of mass 2 kg moves with second part of mass 2 kg moves with 8 m/s speed. If the third part flies off with 4 m/s speed, then its mass is,
3 kg
5 kg
7 kg
7 kg
B.
5 kg
We have,
p1 + p2 + p3 = 0 [ because p = mv]
Therefore,
1 x 12 i + 2 x 8 j + p3 = 0
Now. p3 = m3 v3
This implies,