Class-XI
SECTION A
Attempt
the following questions.
1x20 = 20
1. Can the sum of two vectors be a
scalar?
2. What is the angle between the vectors
A x B & B x A?
3. Why does the direction of motion of a
projectile become horizontal at the highest point of its trajectory?
4. What are horizontal and vertical
components of acceleration of a body thrown horizontally with uniform
speed?
5. Find the dimensional formulae of (i)
Charge (ii) potential
6. Express one micron to meter.
7. Slope of the velocity time graph is
called ____________.
8. Can a body have uniform speed but
still accelerating?
9. What is centripetal force?
10. Write two differences between speed
and velocity.
11. What is the trajectory of a
projectile?
12. What is momentum?
13. What is angle of friction?
14. What is static friction?
15. What is angular momentum?
16. Explain the radius of gyration.
17. What is potential energy?
18. What is a conservative force?
19. What is an elastic collision?
20. Explain coefficient of restitution.
SECTION
B
Attempt
the following questions.
2x9 =18
21.
Explain Newton’s
Second Law.
22.
Explain inertia and
its types.
23. What is a torque?
24. Can the sum of two vectors be a
scalar? Explain.
25.
Determine unit vector which is perpendicular to both A=2i + j + k and B =I – j + 2k?
26. If unit vectors A and B are inclined at an angle θ, then Prove that unit vector|A−B|=
2sin 
27.
Show
that the average K.E of a gas molecule is directly proportional to the
temperature of the gas?
28.
State
four assumptions on which kinetic theory of gas is based?
29.
A
projectile is fired horizontally with a velocity u. Show that its trajectory is
a parabola.
Attempt
the following questions.
3x8= 24
30. A bullet of mass 0.04
kg moving with a speed of 90 m/s enters a heavy wooden block and is stopped
after a distance of 60 cm. What is average resistive force exerted by the block
on the bullet?
31. Derive an expression
for the kinetic energy of a body.
32. If the linear momentum
of a body increases by 20%, what will be the % increase of the kinetic energy
of the body?
33. What is the principle
of conservation of linear momentum?
34. Write the expressions
of parallel axes theorem and perpendicular axes theorem.
35. Derive the relation
between Torque and angular momentum.
36. Calculate for hydrogen at 270C
(a) K.E.of one
gram mole of gas
(b) K.E. of one gram
of the gas
(c) root mean
square velocity of molecule. Molecular weight of hydrogen=2 gram.
37. A cricket ball is thrown at a speed
of 28m/s in a direction 30° above the horizontal. Calculate
(a) maximum height
(b) the time taken by the ball to return to the same level.
(c) the horizontal distance from the
thrower to the point where the ball returns to the same level.
SECTION C
Attempt the following questions.
2x4 =8
38. Prove that in an
elastic one-dimensional collision between two bodies, the velocity of approach
is equal to the velocity of separation after the collision. Hence derive
expressions for the velocities of the two bodies in terms of their initial
velocities before collision.
39. Briefly explain how is a horse able to pull a cart.
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