Work Power and Energy
505 Questions
Start Allen Test
Q301
Allen
WORK
MCQ
A stone of mass m is tied to a string of length $\ell$ at one end and by holding second end it is whirled into a horizontal circle with constant speed v, then work done by the string on the stone will be :-
A.
0
B.
$\left(\frac{\mathrm{mv}^2}{\ell}\right) 2\pi \ell$
C.
$(\mathrm{mg})\cdot 2\pi \ell$
D.
$\left(\frac{\mathrm{mv}^2}{\ell}\right)\ell$
Q302
Allen
WORK
MCQ
A student of Allen is going from samarth to sabal building holding his bag in his hand. Direct distance between these buildings is 50m. Calculate work done by gravity if mass of bag is 3 kg.
A.
750 J
B.
1500 J
C.
Zero
D.
Data insufficient
Q303
Allen
WORK
MCQ
You lift a heavy book from the floor of the room and keep it in the book-shelf having a height 2 m. In this process you take 5 seconds. The work done by you will depend upon :-
A.
Mass of the book and time taken.
B.
Weight of the book and height of the book-shelf
C.
Height of the book-shelf and time taken.
D.
Mass of the book, height of the book-shelf and time taken.
Q304
Allen
WORK
MCQ
Work done by static friction is :
A.
Always zero
B.
Always non-zero
C.
May be zero or non-zero
D.
None of these
Q305
Allen
WORK
MCQ
For the system shown in figure both the block A and B are moving together. If coefficient of friction between both the blocks is $\mu$ , the work done by friction on block B is :-
smooth
smooth
A.
Zero
B.
Negative
C.
Positive
D.
None of these
Q306
Allen
WORK
MCQ
A body of mass M tied to a string is lowered at a constant acceleration of (3g/4) through a vertical distance h. The work done by the string will be.....
A.
$\frac{3}{4}$ Mgh
B.
$\frac{1}{4}$ Mgh
C.
$\frac{-3}{4}$ Mgh
D.
$\frac{-1}{4}$ Mgh
Q307
Allen
WORK
MCQ
The net work done by tension in the figure when the bigger block of mass M touches the ground is :-
A.
$\mathrm{Mgd}$
B.
-(M+m)gd
C.
-mgd
D.
Zero
Q308
Allen
WORK
MCQ
The work done by the frictional force on a pencil in drawing a complete circle of radius $r = 1 / \pi$ metre on the surface by a pencil of negligible mass with a normal pressing force $R = 5N(\mu = 0.5)$ is:
A.
+ 4J
B.
-3J
C.
-2J
D.
-5J
Q309
Allen
WORK
MCQ
Find work done by friction for displacement 'S'?
A.
$\mu_{\mathrm{K}}(\mathrm{mg} + \mathrm{F}\sin \theta)\mathrm{S}$
B.
- $\mu_{\mathrm{K}}(\mathrm{mg} + \mathrm{F}\sin \theta)\mathrm{S}$
C.
$\mu_{\mathrm{K}}(\mathrm{mg} - \mathrm{F}\sin \theta)\mathrm{S}$
D.
- $\mu_{\mathrm{K}}(\mathrm{mg} - \mathrm{F}\sin \theta)\mathrm{S}$
Q310
Allen
WORK
MCQ
The whole wedge and block system is moving as shown in the figure. Block of mass m is not slipping on the wedge. Then which of the following statement is correct (surface between M and m is rough) :-
A.
Work done by normal force on block is zero
B.
Work done by friction force on block is not zero
C.
Work done by normal force on block is not zero
D.
None of these
Q311
Allen
WORK
MCQ
A particle is made to move from the origin in three spells of equal distances, first along the x-axis, second parallel to y-axis and third parallel to z-axis. Each time the force acting on it has constant magnitude of 50 N and always acts along the direction of motion. Work done by this force in the three spells of motion are equal and total work done in the three spells is 300 J. The final coordinates of the particle will be :-
A.
(2, 2, 2) m
B.
(4, 4, 4) m
C.
(6, 6, 6) m
D.
(10, 10, 10) m
Q312
Allen
WORK
MCQ
An object of mass m is sliding down a hill of arbitrary shape and after travelling a certain horizontal path stops because of friction. The work done that a force must perform to return the object to its initial position along the same path would be:-
A.
0
B.
mgh
C.
2mgh
D.
None of these
Q313
Allen
WORK
MCQ
A force $F = (x^{2} + 3x - 5)$ N acts on a 5 kg body along x-axis as a result of which the body gets displaced from x = 0 to x = 3 m. The work done by the force will be ā
A.
35 J
B.
15 J
C.
7.5 J
D.
70 J
Q314
Allen
WORK
MCQ
A force $F = Kx^{3}$ acts on a particle at an angle of $60^{\circ}$ with the x-axis. The work done in displacing the particle from $x_{1}$ to $x_{2}$ will be ā
A.
$\frac{kx^{3}}{3}$
B.
$\frac{k}{3}\left(x_{2}^{2}-x_{1}^{3}\right)$
C.
$\frac{k}{8}\left(x_{2}^{4}-x_{1}^{4}\right)$
D.
$\frac{k}{4}\left(x_{2}^{4}-x_{1}^{4}\right)$
Q315
Allen
WORK
MCQ
A force F acting on an object varies with distance x as shown here.
The work done by the force in moving the object from x = 0 to x = 6m is :-
A.
18.0 J
B.
27 J
C.
36 J
D.
9.0 J
Q316
Allen
WORK
MCQ
Figure gives the acceleration of a 4.0 kg body as it moves from rest along x axis while a variable force acts on it from x = 0m to x = 9m. The work done by the force on the body when it reaches
(i) x=4m and
(ii) x = 7 m shall be as given below
A.
21 J and 33 J respectively
B.
21 J and 15 J respectively
C.
42 J and 60 J respectively
D.
42 J and 30 J respectively
Q317
Allen
WORK
Match the Columns
Calculate the work done for following F-d curves
Match Column-I with Column-II:
Match Column-I with Column-II:
| Column-I | Column-II | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|
A.
(A - R); (B - Q); (C - P); (D - R)
B.
(A - R); (B - P); (C - R); (D - Q)
C.
(A - R); (B - P); (C - Q); (D - R)
D.
(A - P); (B - Q); (C - R); (D - P)
Q318
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
The kinetic energy of a body becomes nine times of its initial value. The new linear momentum will be :-
A.
Four times the initial value
B.
Thrice the initial value
C.
Twice the initial value
D.
Same as the initial value
Q319
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
If the momentum of a body is increased n times, its kinetic energy increases.
A.
n times
B.
2n times
C.
$\sqrt{n}$ times
D.
$n^{2}$ times
Q320
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
If the kinetic energy of a body becomes 4 times of its initial kinetic energy, then the momentum of the body will become :-
A.
$2\sqrt{2}$ times
B.
$\sqrt{2}$ times
C.
2 times
D.
none of these
Q321
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
Two bodies of mass 4kg and 9kg have equal K.E. then the ratio of their momentum is :
A.
3 : 2
B.
2 : 3
C.
4 : 9
D.
16 : 8
Q322
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
2 particles of mass 3 Kg and 5 kg have same momentum, calculate ratio of their K.E.
A.
5:3
B.
3:5
C.
25:9
D.
9:25
Q323
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
If K.E. of body is increased by 300%. Then % change in its 'P' will be
A.
100%
B.
41.4%
C.
17.3%
D.
200%
Q324
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
If the kinetic energy of a body is increased by 800%, the momentum will increase by :-
A.
100%
B.
200%
C.
150%
D.
300%
Q325
Allen
KINETIC ENERGY & WORK ENERGY THEOREM
MCQ
If K.E. of a body increases by 3%, then momentum will increase by :-
A.
1.5%
B.
9%
C.
3%
D.
2%