Class 11 Physics Ch 4 Notes

• Important from class 11 physics ch 4 important questions Punjab Textbook.
• Define work done. Write its formula and unit.
• What is positive and negative work done?
• Define conservative field. Give one example.
• Differentiate between conservative and non-conservative forces. Give examples.
• Define power, Write its formula and unit.
• Define K.E and P.E. Write down their formulae.
• Differentiate between gravitational P.E and Elastic P.E.
• Define work energy principle, Write its mathematical form.
• Define absolute P.E. Write its formula.
• What is escape velocity? Write its value and mathematical form. 
• Differentiate between Geyser and aquifer.
• Important from class 11 physics ch 4 question answer Punjab Textbook.
• State law of conservation of energy. Give one example of energy conversion in our daily life: State law of conservation of energy. Give one example of energy conversion in our daily life. Ans: Law of conservation of energy: Energy neither created not destroyed. It can be converted from one form into another, but the total energy remains constant. Conversion of Mechanical Energy: - The K.E and P.E are the different forms of the energies. The total mechanical energy of the body is equal to the sum of K.E and P.E. P.E may change into K.E, Similarly K.E may also be converted into P.E but the total energy remains constant. Mathematically, we can write. Total energy = K.E + P.E
• Important from class 11 physics ch 4 numericals Punjab Textbook.
• How electrical energy can be obtained by using tides?: Ans: Electrical energy is obtained from tides. Explanation: Gravitational force of the moon produces tides in the sea. The tides raise the water in the sea roughly twice a day. water at high tide can be trapped in a basin by constructing a dam. Dam is filled at high tide. Then, water is released in a controlled way at low tide to derive the turbines. The dam is filled again for next high tide and the fall of water also derive the turbines and turbines run generators. This process is used to generate the electricity from tides.
• What is geothermal energy?
• What is meant by solar constant?
• How can we obtain the energy from biomass?
• Important from class 11 physics ch 4 exercise solutions Punjab Textbook.
• Write sources of energies which are renewable and non-renewable.
• A person holds hold a bag of groceries while standing still, talking to a friend. A car is stationary with its engine running. From the stand point of work, how are these two situations similar?
• Calculate the work done in kilo joules in lifting a mass of 10 kg (at a steady velocity) through a vertical height of 10m.
• A Force F acts through a distance L. the force is then increased to 3F, and then acts through a further distance of 2L. Draw the work diagram to scale.
• Important from class 11 physics ch 4 imp questions Punjab Textbook.
• In which case is work done? When a 50kg of books is lifted through 50cm, or when a 50kg crate is pushed through 2m across the floor with a force of 50N?
• An object has 1J of potential energy. Explain what does it mean?
• A ball of mass m is held at a height h1 above a table. The table top is at height h2 above the floor. One student says that ball has potential energy mgh1, but another says that it is mg (h1 + h2). Who is correct?
• A girl drops a cup from a certain height, which breaks into pieces. What energy changes are involved?
• A body uses a catapult to thrown a stone which accidently smashes a green-house window. List the possible energy changes?