Pdf sheet of Physics formula for class 9 chapter-work and energy

Pdf sheet of Physics formula for class 9 chapter-work and energy

May 19, 2022, 16:45 IST

Formula for Class 9 chapter-work and energy

• Work is said to be done if(l) a force is applied on the object and (ii) the object is displaced from its original position.
• Work done by a force acting on an object is equal to the product of the force (F) and the displacement(s) of the object in the direction of the force, i.e., W = F × s = Fs.
• Work done by a force is positive if the force and the displacement are in same direction.
• Work done by a force is negative if the force and the displacement are in opposite direction.
• Work done by a force is zero if the force is perpendicular to the displacement, le, there is no displacement in the direction of force. Work done by a force is also zero , when there is no displacement at all.
• Work is a scalar quantity.
• The unit of work is joule (J) . One joule work is said to be done on an object when a force of one newton displaces it by one metre along the line of action of the force

1 J = 1 N × 1 m = 1 Nm

Further, 1 kilo joule (1 kJ) = 1000 J and 1 mega joule (1 MJ) = 10 ⁶ J.

Energy

• Energy of an object is defined as its capacity for doing work and it is measured by the total quantity of work it can do. It is a scalar quantity
• The unit of energy is the same as that of work, le., Joule (J) .

Forms of Energy

• Kinetic energy of an object is defined as the energy, which it possesses by virtue of its motion. It is measured by the amount of work that the object can do against an opposing force before it comes to rest.

Derivation of kinetic energy

Now work done = F × s                    …(i)

• Thus, kinetic energy possessed by an object of mass, m and moving with a uniform velocity. V is E _k = 1/2 mv ²

• The kinetic energy (E _K ) of an object is defined as half the product of its mass (m) and the square of the speed (V) of the object, i.e., E _k = 1/2 mv ^2.

Physics Wallah team and faculty members prepared all required formula for physics class 9 of chapter-work and energy in pdf sheet. To score good marks in class 9 solve questions from NCERT with the help of NCERT solutions . Physics Wallah expert uploaded NCERT solutions for class 9 Science. If any students need to take the online test to check their concepts or undertstanding then they can visit Quiz for Work, Power and Energy .

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