Slide 1 : By : S.C.Benjamin, sc.benjamin@yahoo.com Presented by : S.C.Benjamin, M.Sc.(Physics)
Skype ID : refractiveindex
Email : sc.benjamin@yahoo.com
Mobile +919919916577
Kanpur-India
Session 3 : October,14,2011, 9:00 PM
Work : : By : S.C.Benjamin, sc.benjamin@yahoo.com Work : Positive Work
Negative Work
Zero Work
Work while going upstairs
SI unit of work
Define 1 Joule
Energy : By : S.C.Benjamin, sc.benjamin@yahoo.com 3 Energy Forms of Energy (mechanical, electrical, gravitational, chemical, atomic, nuclear, magnetic, sound, light energy)
Potential Energy (mechanical potential, nuclear, chemical potential, gravitational potential, magnetic potential)
Transformation of Energy
Law of Conservation of Energy.
Kinetic Energy ( a form of mechanical energy ) : By : S.C.Benjamin, sc.benjamin@yahoo.com Kinetic Energy ( a form of mechanical energy ) Kinetic energy is energy of motion
Gravitational Potential Energy : By : S.C.Benjamin, sc.benjamin@yahoo.com Gravitational Potential Energy On Earth a 3.57 kg object is lifted a height of 4.74 m. What is the potential energy due to gravity for this object.
An object has a gravitational potential energy of 399.62 J after being lifted a height of 19.59 m on planet Earth. What is the mass of the object?
On Earth a mass of 14.75 kg gains 345.45 J of gravitational potential energy. How high was it lifted?
Gravitational Potential Energy : By : S.C.Benjamin, sc.benjamin@yahoo.com Gravitational Potential Energy Generally potential energy is measured with respect to ground level
It can be measured with respect to other levels as well
Gravitational potential energy of a body doesn’t depend on path through which it was taken to a given height
Energy Transformation ( Sum of Kinetic and Potential Energy of freely falling body remains constant, : By : S.C.Benjamin, sc.benjamin@yahoo.com Energy Transformation ( Sum of Kinetic and Potential Energy of freely falling body remains constant,
Power : By : S.C.Benjamin, sc.benjamin@yahoo.com Power Rate of doing work (power), Power of different appliances
SI unit of Power ( watt)
1 KW = 1000 W
Commercial unit of energy (KWh)
More Numerical Problems : By : S.C.Benjamin, sc.benjamin@yahoo.com More Numerical Problems A porter lifts a luggage of 25 kg from ground and keeps it on his head, 1.7 m above ground. Calculate work done by him on luggage. ( g is 9.8 m/s² )
A car is moving at 20 m/s. Its mass is 1200 kg. What is its kinetic energy ?
Calculate work done in increasing the velocity of a motor cycle from 36 km/h to 72 km/h. The mass of rider and the motor cycle is 200 kg.
A boy of mass 40 kg walks up a flight of 20 steps, each 30 cm high, in 8 s. Calculate power developed by him. (g = 9.8 m/s²)
An air-conditioner is rated 2000 W. How much energy, in KWh, does it consume in 1200 h ?
Density and Relative Density : By : S.C.Benjamin, sc.benjamin@yahoo.com Density and Relative Density Define Density
SI and other units of density
Define Relative Density
Unit of Relative Density (?)
Equations of motion under gravity : By : S.C.Benjamin, sc.benjamin@yahoo.com Equations of motion under gravity
Pressure : By : S.C.Benjamin, sc.benjamin@yahoo.com Pressure
CBSE9 Gravitation : By : S.C.Benjamin, sc.benjamin@yahoo.com CBSE9 Gravitation Newton’s law of gravitation
Newton’s second law of motion (F=ma)
Acceleration due to gravity ( g )
What is weight ?
What is mass ?
Weight on Moon and other planets.
Acceleration due to gravity is independent of mass of falling body (story of Galileo)
Motion under gravity.
Archimedes’ Principle : By : S.C.Benjamin, sc.benjamin@yahoo.com Archimedes’ Principle Whenever a body is immersed in a fluid wholly or partially it suffers a buoyant force which is equal to the weight of the fluid displaced.