Question 1 :
The power of a motor pump is 2 kW. How much water per minute the pump can raise to a height of 10 m? (Given, $g = 10 ms^{-2}$ )

Question 2 :
A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car

Question 3 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2f2f59b460d7261f662.PNG' /> The above image shows, A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force shown in figure. Let us take it that the force acts on the object through the displacement. What is the work done in this case?

Question 5 :
The sum of the potential energy and kinetic energy of the object would be the same at all points. That is, potential energy + kinetic energy = constant.

Question 6 :
The relation connecting the initial velocity $\left(u\right)$ and final velocity $\left(v\right)$ of an object moving with a uniform acceleration a, and the displacement, s is__________.

Question 7 :
An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

Question 8 :
How many kilograms will a man working at the power of 100 W, be able to lift at constant speed of $1 ms^{–1}$ vertically? $(g = 10 ms^{–2})$

Question 10 :
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?

Question 11 :
The energy used in one hour at the rate of 1kW is called 1 kW h.

Question 13 :
Find the energy in kWh consumed in 10 hours by four devices of power 500 W each.

Question 14 :
Which one of the following is not the unit of energy?

Question 15 :
An automobile engine propels a 1000 kg car along a levelled road at a speed of $36 kmh^{–1}$. Find the power if the opposing frictional force is 100 N.

Question 16 :
A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?

Question 20 :
Why is the ceiling and wall behind the stage of good conference halls or concert halls made curved?

Question 21 :
The directions in which the sound is incident and is reflected make equal angles with the normal to the reflecting surface at the point of incidence, and the three are in a different plane. TRUE OR FALSE?

Question 22 :
A sound wave has a frequency of 2 kHz and wave length 35 cm. How long will it take to travel 1.5 km?

Question 23 :
In the inner ear, the pressure variations are turned into electrical signals by?

Question 26 :
An echo is heard in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is $342 m s^{–1}$?

Question 27 :
If you lace a bell into a vacuum chamber with no air in it , will you still be able to hear the sound of the bell ?

Question 28 :
Ultrasounds are used extensively in industries and for medical purposes. TRUE OR FALSE?

Question 29 :
How are the wavelength and frequency of a sound wave related to its speed?