A child swinging a swing. Minimum and maximum heights of swing from earth’s surface are 0.75 m and 2m respectively. The maximum velocity of this swing is
5 m/s
10 m/s
15 m/s
20 m/s
A stationary particle explodes into two particles of masses m1 and m2 which move in opposite directions with velocities v1 ad v2. The ratio of their kinetic energies E1 / E2 is
1
The identical balls A and B moving with velocities + 0.5 m/s and -0.3 m/s respectively collide head on elastically. The velocity of the balls A and B after collision will be respectively
+ 0.5 m/s and +0.3 m/s
-0.3 m/s and +0.5 m/s
+0.3 m/s and 0.5 m/s
-0.5 m/s and +0.3 m/s
An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of water jet. What is the rate at which kinetic energy is imparted to water?
½ mv3
mv3
½ mv2
½ m2v2
A bomb of mass 30kg at rest explodes into two pieces of masses 18kg and 12kg. The velocity of 18kg mass is 6ms-1. The kinetic energy of the other mass is
256 J
486 J
524 J
324 J
300 J of work is done in sliding a 2kg block up an inclined plane of height 10 m. Taking g = 10 m/s2, work done against friction is
200 J
100 J
zero
1000J
A body of mass 1kg is thrown upward with a velocity 20 ms-1.It momentarily comes to rest after attaining a height of 18m. How much energy is lost due to air friction ? ( g = 10 ms-2)
20 J
30 J
40 J
10 J.
A position dependent force F=(7–2x + 3x2) N acts on a small body of mass 2 kg and displaces it from x = 0 to x = 5m.
Work done in joule is
35
70
135
270
Two bodies with kinetic energies in the ratio 4 : 1 are moving with equal linear momentum. The ratio of their masses is
1 : 2
1 : 1
4 : 1
1 : 4
A force acts on a 3.0 g particle in such a way that the position of the particle as a function of time is given by x = 3 t – 4 t 2 + t 3, where x is in meter and t in second. The work done during the first 4 s is
570 mJ
450 mJ
490 mJ
528 mJ