Question Text
Question 1 :
A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has a larger kinetic energy?
Question 2 :
What are the two conditions that are really essential for a work to be done?
Question 3 :
The energy used in one hour at the rate of 1kW is called 1 kW h. TRUE OR FALSE?
Question 4 :
What is the formula of potential energy of an object ?
Question 5 :
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Question 6 :
An electric heater is rated 1500 W. How much energy does it use in 10 hours?
Question 7 :
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Question 8 :
An object of mass 15 kg is moving with a uniform velocity of 4 $ms^{-1}$. What is the kinetic energy possessed by the object?
Question 9 :
A boy of mass 50 kg runs up a staircase of 45 steps in 9 s. If the height of each step is 15 cm, find his power. Take g = 10 m $s^{-2}$.
Question 10 :
Work done on an object by a force would be zero if the displacement of the object is zero.
Question 11 :
1 J is the amount of work done on an object when a force of 1 N displaces it by ____ along the line of action of the force.
Question 12 :
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and final points of the object lie on the same horizonta line. What is the work done by the force of gravity on th object
Question 13 :
Two girls, each of weight 400 N climb up a rope through a height of 8 m. We name one of the girls A and the other B. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?
Question 15 :
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be ($g=10 ms^{-2}$)