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Revision of the chapter of Energy - Grade 8 (ICSE)

Study Slideshow

Neeraj is throwing the javelin. Is he performing work? Explain.

Yes Neeraj performs work because he displaces the javelin by applying force and the javelin moves in the direction of the force.

If 120J of work is done to displace a block by 60 m, calculate the force applied.

2 N

An object is displaced by 2m when a force of 50 N is applied on it. Find the work done on the object.

100 J

A toy car with kinetic energy of 72 J, moved at a speed of 6 m/s. Assuming the mass of the toy car remains the same, what will be its new kinetic energy if the speed is doubled to 12 m/s?

288 J

A shopping cart with mass of 20 kg, has a kinetic energy of 90 J. Assuming the speed of the shopping cart remains the same, what will be its new kinetic energy if the mass is doubled to 40kg?

180 J

Give an example of an object that possesses elastic potential energy.

rubber band or string of the bow or a spring

Gravitational potential energy depends on ------ (Complete the statement)

height and mass of the object and the gravitational pull

Formula for kinetic energy is ------- (Fill in the blanks)

(0.5) x mass x (square of the velocity)

Kinetic energy is possessed by an object when --------- (Complete the statement)

when it is in motion.

Gravitational potential energy is possessed by an object when _____ (Complete the statement)

when it is placed at a height

Calculate the energy stored in a ball of mass 500 g moving with a velocity of 8 m/s

mass = 0.5 kg, Kinetic energy = 16 J

Calculate the energy stored in a stone of mass 2 kg raised to a height of 5000 cm. (Take g = 10m/s^2)

height = 50 m, U = 1000 J

At which position will the potential energy of the car = mechanical energy of the system? Explain your answer.

At position A. Since the height of the track will be maximum at position A

At which position will the kinetic energy of the car = mechanical energy of the system? Explain your answer,

At position B, the track is at the ground level. So all the potential energy will be converted to KE

Calculate the mechanical energy of the system if the mass of the coaster = 10 kg and g=10 m/s^2

mechanical energy = 10,000 J