## Class XI Physics Important Questions

1. Write the dimensions of x and y in the equation.

* F *=__ mx__ + *Y * where

F = Force, m = mass and t = time.

t

2. An object dropped by a person in a lift

remains at the same position relative to the lift and the person. What can you

say about the motion of the lift.

3. If two forces 3 Nand 9 N are acting on a body of mass 12 kg,

draw a diagram to illustrate what orientation of the two forces will produce the

least acceleration and

calculate the acceleration.

4. Two bodies of different masses have same momentum. Which one

will have greater kinetic energy the lighter one or the heavier one. Justify.

5. State the theorem of perpendicular axes of moment of inertia.

6. Write the two essential conditions for a given oscillatory motion to be

SHM.

7. What are beats? How are they produced?

8. Draw a graph showing the variation of amplitude with

frequency for a forced

oscillation and hence define resonance.

10 Define relative velocity. A boy wishes 10 swim across a river

In the shortest possible time? At what angle should he swim

if

the river is flowing with a velocity 10 m/s and

the boy can swim at 5 *m/s.*

11. A fighter plane is flying horizontally at an altitude of 1

km at a speed of 200 km/h. At what horizontal distance from a target should it

release a bomb so as to hit the

target. Take 9 = 10 *m/s*^{2}

11a. Calculate the angle of projection for which the horizontal

range is equal to the

maximum height attained.

12. a. Explain why does a person run a little. while getting

down from a moving bus.

b. Why is it advised to bend knees

while landing on floor after jumping from a height.

13. Show

that

work done in increasing the speed of a body

is equal to the change in Kinetic Energy produced.