1. Define one watt of power.
2. Name twy physical quantities whose unit is Joule.
3. What is gravitational potential energy?
4. What is the commercial unit of energy? Define it.
5. Give one example where work done on an object is negative.
6. What work is said to be done to increase the velocity of a car from 15 km/h to 30 km/h, if the mass of the car is 1000 kg?
7. A body possess potential energy of 460 J whose mass is 20 kg and is raised to a certain height. What is the height when g = 10 m/s2.
8. Derive the formula for kinetic energy.
9. With pendulum as an example the law of conservation of energy.
10. Derive the formula for potential energy.
Answers
Answer:
1) The watt is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer.
2) work and energy.
3)Gravitational energy is the potential energy a physical object with mass has in relation to another massive object due to gravity.
4)commercial unit of energy is Kilo Watt Hour.
5) ball is thrown in upwards direction.
6)u=15km/h
v=30km/h
Mass=1000 kg
W=?
1/2×1000×((30) ²-(15²)
1/2×1000(900−225)
= 21
1/2 ×1000(675)
K.E.=337500J
∴ Work done =337500 Joule.
7)The potential energy is the product of the mass of the object, gravitational acceleration and height. Hence, the raised height is the 2.3 m.
8)Derivation of Kinetic Energy Formula by Calculus
Work done = Final K.E. - Initial K.E. The work done by a force is a measure of the change in kinetic energy of the body which proves the work-energy principle.
9)example of conservation of energy : ... When the bob reaches the centre position A, it has only kinetic energy (but no potential energy). As the bob goes from position A towards position C, its kinetic energy goes on decreasing but its potential energy goes on increasing.
Answer:
1) The watt is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second, and is used to quantify the rate of energy transfer.
2) work and energy.
3)Gravitational energy is the potential energy a physical object with mass has in relation to another massive object due to gravity.
4)commercial unit of energy is Kilo Watt Hour.
5) ball is thrown in upwards direction.
6)u=15km/h
v=30km/h
Mass=1000 kg
W=?
1/2×1000×((30) ²-(15²)
1/2×1000(900−225)
= 21
1/2 ×1000(675)
K.E.=337500J
∴ Work done =337500 Joule.
7)The potential energy is the product of the mass of the object, gravitational acceleration and height. Hence, the raised height is the 2.3 m.
8)Derivation of Kinetic Energy Formula by Calculus
Work done = Final K.E. - Initial K.E. The work done by a force is a measure of the change in kinetic energy of the body which proves the work-energy principle.
9)example of conservation of energy : ... When the bob reaches the centre position A, it has only kinetic energy (but no potential energy). As the bob goes from position A towards position C, its kinetic energy goes on decreasing but its potential energy goes on increasing.
Explanation: