Work Energy and Power Test

Result

Work Energy and Power Test - 56

Score
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Weekly Quiz Competition

Question 1
1 / -0

A particle moves along the x-axis from x=0 to x=5 m under the influence of a force given by $$F=\left( { 7-2x+3x }^{ 2 } \right) N.$$ The work done in the process is

A
70 J

B
270 J

C
35 J

D
135 J

Solution
Question 2
1 / -0

A force $$F_1$$ on a body of 2 kg produces an acceleration of $$2.5 m/m^2$$ and other force $$F_2$$ acting on another body of mass 5 kg produces an acceleration of $$2 m/s^2$$. The ratio of $$F_2/F_1$$ is

A
$$2$$

B
$$4$$

C
$$6$$

D
$$8$$

Solution

Given,
$$m_1=2kg$$
$$a_1=2.5m/s^2$$
$$m_2=5kg$$
$$a_2=2m/s^2$$

Ratio, $$\dfrac{F_2}{F_1}=\dfrac{m_2a_2}{m_1a_1}$$

$$\dfrac{F_2}{F_1}=\dfrac{5\times 2}{2\times 2.5}=2$$
The correct option is A.
Question 3
1 / -0

A force $$\vec { F } = 2 x \hat { i } + 3 y ^ { 2 } \hat { j } \mathrm { N }$$ where x and y are in meter, acts upon a particle. Find work done (in J) by this force in displacing the particle from (1 m, 2 m, 5 m) to (2 m, 3 m, 2 m).

A
24

B
16

C
28

D
22

Solution
Question 4
1 / -0

The amount of work done in stretching a wire by 10N force can cause an elongation of $$2×{ 10 }^{ -2 }m$$ will be

A
10 J

B
1 J

C
0.1 J

D
0.01

Solution
Question 5
1 / -0

Velocity-time graph of a particle of mass 2 kg moving in a straight line is as shown in figure. Work done by all the forces on the particle during the motion is:

A
$$400 J$$

B
$$-400 J$$

C
$$-200 J$$

D
$$200 J$$

Solution
Question 6
1 / -0

A particle is displaced from a position $$(2\hat { i } -\hat { j } +\hat { k } )$$ metre to another position $$(3\hat { i } +2\hat { j } -2\hat { k } )$$ meter under the action of force $$(2\hat { i } +\hat { j } -\hat { k } )$$ N. Work done by the force is:

A
8 J

B
10 J

C
12 J

D
36 J

Solution
Question 7
1 / -0

A balloon with its contents weighing 160 N is moving down with an acceleration of g/2 $${ ms }^{ -2 }$$ the mass to be removed from it so that the balloon moves up with an acceleration of g/3$${ ms }^{ -2 }$$ is

A
5 kg

B
10 kg

C
6 kg

D
3 kg

Solution
Question 8
1 / -0

In the figure, at the free end of the light string, a force $$F$$ is applied to keep the suspended mass of $$18 $$\mathrm { kg }$$ at rest. Assuming

A
$$240 N$$

B
$$120 M$$

C
$$180 M$$

D
$$240 M$$

Solution

$$3T=180$$
or, $$T=60 N$$
Now, $$F=T=60 N$$
Therefore ,total force on ceiling is $$4T=240 N$$
Hence, Option $$A$$ is correct.
Question 9
1 / -0

The breaking strength of a string is 55 kg wt. The maximum permissible speed of a stone of mass 5 kg which revolved in a vertical circle of radius 4 m with the help of is the string is g=10 $$ {s}^{2} $$.

A
$$

10 \mathrm{m} / \mathrm{sec}

$$

B
$$

15 \mathrm{m} / \mathrm{sec}

$$

C
$$

20 \mathrm{m} / \mathrm{sec}

$$

D
$$

25 \mathrm{m} / \mathrm{sec}

$$
Question 10
1 / -0

A force of $$ \left(4 x^{2}+3 x\right) $$ N acts on a particle which displaces it from $$ x=2 m $$ to $$ x=3 \mathrm{m} $$.
The work done by the force is

A
$$32.8 J$$

B
$$3.28 J$$

C
$$0.328 J$$

D
zero

Solution