Physics full notes of class 11 ch5

The correct options are with their questions numbers.

1 = D , 2 = D , 3 = C , 4 = D , 5 = C , 6 = C , 7 = C , 8 = A , 9 = B

Physics full notes of class 11 ch5 McQs end.

**Short Questions**

**Question 1 Answer:** The fly wheel of an engine is made heavy in the rim for increasing the moment of inertia of the fly wheel. We know that moment of inertia is given by ,

I = mr (r square)

Equation shows that if we increase the mass , the moment of inertia also increases. Now if the flywheel gains or loses some national kinetic energy K.E = 1/2 Iw (w square) ,then due to large value of moment of inertia the angular velcoity ‘w’ changes very slowly. The result is that the fly wheel helps in maintaining uniform rotational motion.

**Question 2 Answer:** A rifle barrel has a spiral groove. Which imparts spin to the bullet due to which the bullet acquires angular momentum about an axis parallel to the barrel. Since angular momentum is conserved which keeps the bullet pointing stably in this direction and so improve the accuracy. That is the distant target is hit accurately.

**Question 3 Answer:** Yes, it is possible for a person to distinguish between a raw egg and a hard boiled one by spinning each one a table.

When a raw egg is spin the yoke of the egg being denser moves away from the axis of rotation. Now accordning to the relation I = mr ( r square) , the moment of inertia of raw egg increases. Therefore it is much more difficult to spin the egg.

On the other hand, the yoke of a hard boiled egg is fixed. When the egg is spin its moment of inertia does not increase and hence it spins more easily.

**Question 4 Answer:** When a body moves in a circle with uniform speed ,then the direction of its velcoity changes from point to point. This change in direction of velocity is always towards the center of circle. Therfore, the centripetal acceleration is always directed towards the center of the circle.

**Questions 5 , 6 and 10 is missing we will add that in the end of last chapter.**

**Question 7 Answer :** The minimum number of geo stationary satellites required for global coverage of T.V transmisson is three.

Since one geo stationary satellite covers 120 degree of longitude, so for the whole populated earth’s surface there must be 360 degree of longitude. Hence , the T.V transmission can be covered by three correctly positioned geo-stationary satellites.

**Question 8 Answer:** The moment of inertia plays the same role in rotational motionas the mass plays in linear motion. The greater the moment of inertia of a body the greater is the difficulty in starting or stoping its rotation. It is a measure of inertia in rotational motion and is also called rotational inertia.

As in case of linear motion the interia measure opposition os a body to change its state of rest or its uniform linear motion.

**Question 9 Answer:** We know that the moment of inertia depends upon the mass of the body and the distance ‘r’ from the axis of the rotation. in case of mass we cans ay that greater the mass the greater will be moment of inertia and vice versa.

Now when water is added to the beaker the mass of the system increases due to which moment of inertia of the system increases.

Thus the coasting rotating system becomes slow down as water drops into the beaker.

**Question 11 Answer:** We know that the moment of inertia depends upon the mass of the body and the distance ‘r’ from the axis of the rotation I = mr (r square).

The mass of the heavier wheel is large value due to which it rotational inertia is also greater. So when a tractor moves with uniform velocity , its heavier wheel rotates slowly than its lighter wheel due to alrge amount of moment of inertia.

Physics full notes of class 11 ch5 short questions end.

Read out previous chapter 4 too or next jump to chapter 6