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#### Nature of Physical World and Measurement- 1 marks ; part-2

11th Standard

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 10
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. What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?

(a)

$\sqrt{2gR}$

(b)

$\sqrt{3gR}$

(c)

$\sqrt{5gR}$

(d)

$\sqrt{gR}$

3. A wind-powered generator converts wind U(x) energy into electric energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. For wind speed v, the electrical power output will be proportional to,

(a)

v

(b)

v2

(c)

v3

(d)

v4

4. A particle which is constrained to move along x-axis, is subjected to a force in the same direction which varies with the distance x of the particle from the origin as F(x) =kx + ax3. Here, k and a are positive constants. For x≥0, the functional form of the potential, energy U(x) of the particles

(a)

(b)

(c)

(d)

5. A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then, the long piece will have a force constant of

(a)

$\frac{2}{3}$k

(b)

$\frac{3}{2}$k

(c)

3k

(d)

6k

6. If the force and the displacement are at an angle of 180°, then work done is:

(a)

F.S

(b)

-F.S

(c)

0

(d)

F-S

7. Two springs have their force constants as k1 and k2 (k1 > k2). When their lengths are increased by the same amount, then the work done on the two springs will be such that

(a)

W1> W2

(b)

W1 <W2

(c)

W1= W2

(d)

W2 = 0

8. A suitcase is dragged 30 m along a floor by a force of 10 N inclined at an angle 30° to the floor. The work done on the suitcase is

(a)

$150\sqrt 2J$

(b)

150J

(c)

$150\sqrt 3J$

(d)

$\sqrt 3J$

9. Non-conservative force is

(a)

frictional force

(b)

viscous force

(c)

air resistance

(d)

all the above

10. The ratio of velocities of equal masses in an inelastic collision with one of the masses is stationary is

(a)

$\frac { 1-e }{ 1+e }$

(b)

$\frac { 1+e }{ e-1 }$

(c)

(1 + e) (1 - e)

(d)

$\frac { e-1 }{ e+1 }$