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#### Nature of Physical World and Measurement-1 marks, 2marks, 3marks, 5marks; part2

11th Standard

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 50
Part-A
10 x 1 = 10
1. A uniform force of (2$\hat { i }$+$\hat { j }$) N acts on a particle of mass 1 kg. The particle displaces from position (3$\hat { j }$+$\hat { k }$) m to (5$\hat { i }$+3$\hat { j }$) m. The work done by the force on the particle is

(a)

9 J

(b)

6 J

(c)

10 J

(d)

12 J

2. If the linear momentum of the object is increased by 0.1% then the kinetic energy is Increased by

(a)

0.1 %

(b)

0.2 %

(c)

0.4 %

(d)

0.01 %

3. A particle is placed at the origin and a force F = kx is acting on it (where k is a positive constant). If U (0) = 0, the graph of U(x) versus x will be (where U, is the potential , energy function)

(a)

(b)

(c)

(d)

4. An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of the water of the jet. What is the rate at which kinetic energy is imparted to water?

(a)

${{1}\over{2}}{m}{v}^{2}$

(b)

mv3

(c)

${{1}\over{2}}{m}{v}^{3}$

(d)

${{1}\over{2}}{m}{v}^{2}$

5. The spring of the watch when wound possesses ____________ energy.

(a)

kinetic

(b)

potential

(c)

neither (a) nor (b)

(d)

both (a) and (b)

6. The energy possessed by a body by its state of strain is called as:

(a)

kinetic energy

(b)

mechanical energy

(c)

potential energy

(d)

none

7. Power is given by:

(a)

a product of force and velocity

(b)

a product of work and time

(c)

a product of force and distance

(d)

a product of work and displacement

8. If the momentum of a body is increased by 100%, then the percentage increase in its kinetic energy is

(a)

100%

(b)

300%

(c)

200%

(d)

500%

9. Two equal masses m1 and m2 moving along the same straight line with velocities + 3 m/s and -5 m/s respectively collide elastically. Their velocities after the collision will be respectively

(a)

- 4 m/s and +4 m/s

(b)

+4 m/s for both

(c)

- 3 m/s and +5 m/s

(d)

- 5 m/s and + 3 m/s

10. In inelastic collision, which is conserved

(a)

linear momentum

(b)

total energy

(c)

both (a) and (b)

(d)

either (a) or (b)

11. Part-B
5 x 2 = 10
12. Explain the characteristics of elastic and inelastic collision.

13. A bullet of mass 20 g strikes a pendulum of mass 5 kg. Th e centre of mass of pendulum rises a vertical distance of 10 em. If the bullet gets embedded into the pendulum, calculate its initial speed

14. When is the exchange of energy maximum during an elastic collision?

15. If energy is neither created nor destroyed, what happens to the so much energy spent against friction?

16. A bullet of mass 50 g is fired from below into a suspended object of mass 450 g. The object rises through a height of 1.8 m with bullet remaining inside the object. Find the speed of the bullet. Take g = 10 ms-2.

17. Part-C
5 x 3 = 15
18. A ball of mass0.1 kg collides elastically with a ban of unknown mass at rest. If 0.1 kg ball rebounds at 1/3 of the original speed, find the mass of other ball.

19. Spring A and B are identical except that A is stiffer than B, i.e., force constant kA > kB. In which spring is more work expended if they are stretched by the same amount?

20. Two objects of masses 2 kg and 4 kg are moving with the same momentum of 20 kg m s-1
(a) Will they have same kinetic energy?
(b) Will they have same speed?

21. An object of mass 2 kg is taken to a height 5 m from the ground (g = 10 ms-2 ).
(a) Calculate the potential energy stored in the object.
(b) Where does this potential energy come from?
(c) What external force must act to bring the mass to that height?
(d) What is the net force that acts on the object while the object is taken to the height 'h'?

22. An object of mass 2 kg attached to a spring is moved to a distance x = 10 m from its equilibrium position. The spring constant k = 1N m-1 and assume that the surface is frictionless.
(a) When the mass crosses the equilibrium position, what is the speed of the mass?
(b) What is the force that acts on the object when the mass crosses the equilibrium position and extreme position x = ± 10m?

23. Part-D
3 x 5 = 15
24. Explain with graphs the difference between work done by a constant force and by a variable force

25. What is inelastic collision? In which way it is different from elastic collision. Mention few examples in day to day life for inelastic collision.

26. A 10kg ball and 20kg ball approach each other with velocities 20 ms-1 and 10 ms-1 respectively. What are their velocities after collision if the collision is perfectly elastic?