When a body falls freely towards the earth, then its total energy
increases
decreases
remains constant
first increases and then decreases
When a ball is thrown up vertically with velocity vo it reaches a maximum height of h. If one wishes to triple the maximum height then the ball should be thrown with velocity.
vo√3
3vo
9vo
(3/2)vo
Two bodies of masses 0.1kg and 0.4kg move towards each other with velocities 1 m/s and 0.1m/s respectively. After collision they stick together. In 10sec the combined mass travels?
120 m
0.12 m
12 m
1.2 m
The work done on an object does not depend upon the
displacement
force applied
angle between force and displacement
initial velocity of the object
The graph between the resistive force F acting on a body and the distance covered by the body is shown is shown in the figure. The mass of the body is 60 kg and the initial velocity is 3m/s. When the distance covered by the body is 4m, its kinetic energy will be
250 J
230 J
200 J
220 J
In case of negative work, the angle between the force and displacement is
How are Joule (J) and ergs (erg) related?
None of these
A metal ball of mass 2 kg moving with speed of 36km/h is having a collision with a stationary ball of mass 3kg. If after collision, both the balls move together, the loss in kinetic energy due to collision is
80 J
40 J
60 J
160 J
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be
6 ×10^{3} J
6 J
0.6 J
zero
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
does not change
becomes twice to that of initial
becomes 4 times that of initial
becomes 16 times that of initial
A bullet is fired from a riffle. If the riffle recoils freely, then the kinetic energy of the rifle will be?
same as that of bullet
more than that of bullet
less than that of bullet
none of these
A vertical spring with force constant 'k' is fixed on a table. A ball of mass 'm' at height 'h' above the free upper end of the spring falls vertically on the spring so that the spring is compressed by a distance d. The net work done in the process is.
mg(h + d) - (1/2)kd^{2}
mg(h - d) - (1/2)kd^{2}
mg(h - d) + (1/2)kd^{2}
mg(h + d) (1/2)kd^{2}
A body is falling from a height h. After it has fallen a height h/2 , it will possess
only potential energy
only kinetic energy
half potential and half kinetic energy
more kinetic and less potential energy
Option 3
A block of mass 10kg is moving in x-direction with a constant speed of 10 m/s . It is subjected to a retarding force F=-0.1 x joule / meter during its travel from x=20 meter to x=30 meter. Its final kinetic energy will be.
475 J
450 J
275 J
250 J
A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg, which is moving in the same direction with a velocity of 4m/s. If the collision is elastic their velocities after collision will be respectively?
12m/s, 6m/s
8 m/s, 10 m/s
6m/s, 12m/s
10m/s, 8m/s
A 12 HP motor has to be operated 8 hours/day. How much will it cost at the rate of 25 paisa/kWh in 20 days
Rs. 350
Rs. 358
Rs. 375
Rs. 397
For inelastic collision between two spherical rigid bodies
the total kinetic energy is conserved
the total potential energy is conserved
the linear momentum is not conserved
the linear momentum is conserved
An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same
acceleration
momenta
potential energy
kinetic energy
A weight lifter lifts 300 kg from the ground to a height of 4m in 3 seconds. The average power generated by him is
5880 W
3920 W
1960 W
4410 W
A shell of mass 'm' moving with velocity v suddenly break into two pieces the part having mass m/3 remains stationary. The velocity of other part will be?
(2/3) v
(7/5) v
(3/2)v
none of these