Law of Conservation of Energy
Trending Questions
State the principle of conservation of energy.
What is the law of equipartition of energy?
A ball of mass 0.20 kg is thrown vertically upwards with an initial velocity of 20 m s−1.Calculate the maximum potential energy it gains as it goes up.
Show that the sum of kinetic energy and potential energy(i.e., total mechanical energy) is always conserved in the case of freely falling body under gravity (with air resistance neglected) from a height h by finding it when (i) the body is at the top, (ii) the body has fallen a distance x, (iii) the body has reached the ground.
What does the law of conservation of energy state?
Give reasons for your answer.
A ball is placed on a compressed spring.What form of energy does the spring possess? On releasing the spring, the ball flies away.Give a reason.
The Law of conservation of mechanical energy is valid only when…..
The diagram given below shows a ski jump. A skier weighing 60 kgf stands at A at the top of the ski jump. He moves from A and takes off for his jump at B.
(a) Calculate the change in the gravitational potential energy of the skier between A and B.
(b) If 75% of the energy in part (a) becomes kinetic energy at B, calculate the speed at which the skier arrives at B.(Take g=10 ms−2.
Energy can exist in several forms and may change from one form to another.For each of the following, state the energy changes that occur in:
(a) the unwinding of a watch spring,
(b) a loaded truck when started and set in motion,
(c) a car going uphill,
(d) photosynthesis in green leaves,
(e) charging of a battery,
(f) respiration,
(g) burning of a match stick.
(h) explosion of crackers.
The only mechanical energy possessed by a moving train is the potential energy.
True
False
A metal ball of mass 2 kg is allowed to fall freely from rest from a height of 5 m above the ground.
(a) Taking g=10 m s−2, calculate:
(i) the potential energy possessed by the ball when it is initially at rest.
(ii) the kinetic energy of the ball just before it hits the ground?
(b) What happens to the mechanical energy after the ball hits the ground and comes to rest?
Law of conservation of energy states that
Energy can neither be created nor destroyed.
Energy can neither be created nor destroyed. It may be transformed from one form to another form
Energy can neither be created nor destroyed. It may be transformed from one form to another form, but the total energy of any system remains constant.
Energy can neither be created nor destroyed. It may be transformed from one form to another form, but the total energy of an isolated system remains constant.
A body of mass 1 kg falls from a height of 5 m. How much energy does it possess at any instant? (Take g=9.8 m/s2)
49J
50J
0J
48J
Define the kinetic energy of an object. Show that work done by a force on an object is equal to the change in kinetic energy of the object.
What do you understand by the conservation of mechanical energy? State the condition under which the mechanical energy is conserved.
A body is thrown vertically upwards, Its velocity keeps on decreasing.What happens to its kinetic energy as its velocity becomes zero?
A pendulum is oscillating on either side of its rest position.The correct statement is:
(a) It has only the kinetic energy at its each position.
(b) It has the maximum kinetic energy at its extreme position.
(c) The sum of its kinetic and potential energies remains constant throughout the motion.
Name two examples in which the mechanical energy of a system remains constant.
A ball of mass m is thrown vertically up with an initial velocity so as to reach a height h.The correct statement is :
(a) Potential energy of the ball at the ground is mgh.
(b) Kinetic energy of the ball at the ground is zero.
(c) Kinetic energy of the ball at the highest point is mgh.
(c) Potential energy of the ball at the highest point is mgh.
A shot put player throws a shot put of mass 3 kg. If it crosses the top of the wall of 2m high at a speed of , compute the total mechanical energy gained by the shot put when it crosses the wall. given,
Which of the following statement(s) is/are true about a freely falling body?
1. Total energy is constant.
2. Potential energy changes to kinetic energy.
3. Potential energy decreases.
4. Kinetic energy increases.
only 2, 3, 4
1, 2, 3, 4
only 1, 2
only 3, 4
We know that If a ball of mass 1 kg is kept at a height 10 m possess potential energy mghi.e. (1×10×10)=100 J. (Taking earth surface as reference, where m = mass of object, g = acceleration due to gravity, h = height of object from earth surface.) what will be the kinetic energy of the ball when the ball is allowed to freely fall from a height 10m just before it hits the ground? (take g = 10 m/s2 and neglect air drag)
100 J
50 J
10 J
0 J
What is meant by the mechanical effect of an electric current?
Is the law of conservation of energy valid in every situation?
If a ball is dropped from some height H from the ground then which one is the correct graph for total energy vs height from the ground?
A 4 kg projectile is launched from a height of 2 m with an initial speed of 12 m/s. Find its speed when it is at a maximum height of 3 m above the ground.
√31 ms−1
3√31 ms−1
2√31 ms−1
4√31 ms−1
- No energy
- Electrical
- Kinetic
- Potential
Solar panels are used for harnessing solar energy. This solar energy is then used to charge an electric cell and this electric cell is used to move a toy. What are the energy changes that take place?
Solar energy - Chemical energy - Kinetic energy
Kinetic energy - Solar energy - Chemical energy
Chemical energy - Kinetic energy - Solar energy
Potential energy - Chemical energy - Solar energy