Question 1 :
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?

Question 2 :
The weight of a person on a planet A is about half that on the earth. He can jump upto 0.4 m height on the surface of the earth. How high he can jump on the planet A?

Question 3 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2e2f59b460d7261f64c.png' /> In the above fig. A force of 5 N is acting on an object. The object is displaced through 2 m in the direction of the force. If the force acts on the object all through the displacement, then what is the work done?

Question 4 :
<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 :
An electric bulb of 60 W is used for 6 h per day. Calculate the ‘units’ of energy consumed in one day by the bulb.

Question 6 :
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 7 :
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 8 :
The work done on an object does not depend upon the

Question 10 :
The energy possessed by a body due to its change in position or shape is called the potential energy.

Question 11 :
Is it possible that an object is in the state of accelerated motion due to external force acting on it, but no work is being done by the force.

Question 12 :
The kinetic energy of a body moving with a certain velocity is ________ to the work done on it to make it acquire that velocity.

Question 13 :
An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same

Question 14 :
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 15 :
The Jog Falls in Karnataka state are nearly 20 m high. 2000 tonnes of water falls from it in a minute. Calculate the equivalent power if all this energy can be utilized? $(g = 10 ms^{–2})$

Question 17 :
If any explosion takes place at the bottom of a lake, what type of shock waves in water will take place?

Question 18 :
Megaphones or loudhailers, horns, musical instruments such as trumpets and shehanais, are all designed to send sound in a particular direction without spreading it in all directions. TRUE OR FALSE?

Question 19 :
If velocity of sound in air is $340ms^{-1}$, calculate wavelength when frequency is 256 Hz.

Question 21 :
Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?

Question 22 :
Before playing the orchestra in a musical concert, a sitarist tries to adjust the tension and pluck the string suitably. By doing so, what is he adjusting?

Question 23 :
Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called?

Question 24 :
Ultrasounds are used extensively in industries and for medical purposes. TRUE OR FALSE?

Question 26 :
How do you think sound is produced by your school bell?

Question 27 :
The bone(s) which amplify the vibrations reached to our ear is(are)?

Question 28 :
When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remain the same. Do you hear echo sound on a hotter day?

Question 29 :
When we change feeble sound to loud sound, we increase its ___.