Ch 8 Physics Class 9
Important easy to understand Notes of Ch 8 Physics Class 9 English Medium written by Professor Sulman Arif Suib. These notes are very helpful in the preparation of Physics for students of the 9th class Physics English Medium and these are according to the paper patterns of all Sindh Book Boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Define work. Give its formula and unit.
- Define energy.
- Differentiate between Kinetic energy and potential energy.
- State law of conservation of energy.
- Write short note on: Fossil Fuel Energy, Hydroelectric Energy, Solar Energy, Nuclear Energy, Geothermal Energy, Wind Energy, Biomass Energy, Tidal Energy.
- Differentiate between renewable and non-renewable energy sources.
- Define Efficiency. Give formula for efficiency.
- Define Power. Give formula for efficiency.
- Derive P.E = mgh
- Solved Numerical of the exercise Ch 8 Physics Class 9.
- How much work is needed to move a horizontally a body 20m by a force of 30N, the angle between body and the horizontal surface is 60°?
- Find the work done when a force of 50N is applied to move a trolley at a shopping mall through a distance of the 200m? Assume the angle of to be of 0° between the force and the distance that trolley moved. Cos0° =1.
- How much work is done, if a crate is moved at a distance of 50m when a force of 30N is applied along the surface.
- A ball of mass 400gram, strikes the wall of velocity 4m/sec. How much is the kinetic energy of the ball at the time it is strikes the wall?
- If LED screen of mass 10kg is lifted up and kept it on a cupboard of height 2m. Calculate the potential energy is stored in the LED screen.
- Calculate the potential energy of 10kg water raised to the tank at the roof of a home 4m high.
- A ball of mass 50 gram is raised to a height of 7m from the ground. Calculate its gravitational potential energy?
- Calculate the efficiency of a machine which consumes 200J of energy and performs 50J of work.
- Calculate the power of a machine. If the machine performs A 900joules of work in 30minutes.
- If the efficiency of a machine is 70% and its output is 100joule then calculate its input.
- Which machine is more efficient, machine "A" which has an output of 200J after consuming 400J of energy or machine "B" which has an output of 300J after consuming 450J of energy.
- The energy of 600J dissipated by a bulb in a 50 minutes. Find the power of a bulb.
- Calculate the power of a machine, if it does 40 joules of work in 10sec.
- A student of weight 400N takes 5 seconds to climb up and obstacle of height 2m. Calculate the power consumed?
- If a machine consumes 2500J of energy per hour then what will be its power?