Work Energy and Power Test

Result

Work Energy and Power Test - 73

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Weekly Quiz Competition

Question 1
1 / -0

In a simple hydraulic press, the cross-sectional area of the two cylinders is $$5\times 10^{-4}m^2$$ and $$10^{-2}m^2$$, respectively. A force of $$20$$N is applied at the small plunger. How much work is done by the operator, if the smaller plunger moves down $$0.1$$m?

A
40 J

B
2 J

C
20 J

D
200 J

Solution
Question 2
1 / -0

A vertical spring of force constant $$100$$N/m is attached with a hanging mass of $$10$$kg. Now an external force is applied on the mass so that the spring is stretched by additional $$2$$m. The work done by the force F is? $$(g=10 m/s^2)$$

A
$$200$$ J

B
$$400$$ J

C
$$450$$ J

D
$$600$$ J

Solution

Given that,

Spring constant $$k=100$$

Mass $$m=10\,kg$$

Stretching $$x=2\,m$$

We know that,

The work done is

$$ W=\dfrac{1}{2}k{{x}^{2}} $$

$$ W=\dfrac{1}{2}\times 100\times 4 $$

$$ W=200\,J $$

Hence, the work done is $$200\ J$$
Question 3
1 / -0

A block is attached with a spring and is moving towards a fixed wall with speed V as shown in figure. As the spring reaches the wall, it starts compressing. the work done by the spring on the wall during the process of compression is

A
$$\frac{1}{2} mv^2$$

B
$$mv^2$$

C
kmv

D
zero

Solution
Question 4
1 / -0

A ball moving with a velocity of 6 m/s strikes an identical stationary ball. After collision each ball moves at an angle of $$30^{\circ}$$ with the original line of motion. What are the speeds of the balls after the collision?

A
$$\frac{\sqrt{3}}{2}m/sec$$

B
3 m/sec

C
2$$\sqrt{3}$$ m/sec

D
$$\sqrt{3}$$ m/sec

Solution
Question 5
1 / -0

The diagram shows a barrel of weight $$1.0 \times 10^3$$ N on a frictionless slope inclined at $$30^0$$ to the horizontal. A force is applied to the barrel to move it up the slope at constant speed. The force is parallel to the slope. What s the work done in moving the barrel a distance of 5.0 m up the slope?

A
$$1.0 \times 10^4$$ J

B
$$2.5 \times 10^3$$ J

C
$$4.3 \times 10^3$$ J

D
$$5.0 \times 10^3$$ J

Solution
Question 6
1 / -0

A practical of mass $$m$$ is moving in $$X-Y$$ plane under the action of a central force $$\overrightarrow { F }$$ in such a manner that at any instant $$t$$, the components of the velocity of the particle are-$${ v }_{ x }=4\cos { t,{ v }_{ y }=4sint} $$Then the amount of the work done by the force in a time interval $$t=0$$ to $$t$$ is-

A
$$zero$$

B
$$4Ft$$

C
$$ \frac { 4F }{ t } $$

D
None of the above

Solution
Question 7
1 / -0

A uniform rod AB of length land mass m is lying on a smooth table. A small particle of mass m strike the rod with a velocity $$V_{0}$$ at point C a distance X from the centre O. The particle comes to rest after collision. The value of x, so that point A of the rod remains stationary just after collision is:

A
$$L/3$$

B
$$L/6$$

C
$$L/4$$

D
$$L/12$$

Solution
Question 8
1 / -0

The collision of two balls of equal mass takes place at the origin of co-ordinates. Before collision, the components of velocities are ($$y_{x}=50 cm/s$$, $$v_{v}=0)$$ and $$(v_{x}=-40 cm/s)$$ and velocity components ($$v_{x}$$ and $$v_{y}$$ respectively) of the second ball are:

A
$$30\ and\ 10 cm/s$$

B
$$10\ and\ 30 cm/s$$

C
$$5\ and\ 15 cm/s$$

D
$$15\ and\ 5 cm/s$$

Solution
Question 9
1 / -0

Two identical balls are released from positions as shown. They collide elastically on horizontal surface. Ratio of heights attained by A & B after collision is( All surface are smooth,neglect energy loss at M & N)

A
1:4

B
2:1

C
4:13

D
2:5

Solution
Question 10
1 / -0

A car weighing 1 ton is moving twice as fast as another car weighing 2 ton. The kinetic energy of the one-ton car is

A
less than that of the two-ton car is

B
some as that of the two-ton car is

C
more than that of the two-ton car is

D
impossible to compare with that of the two-ton car unless the height of each

Solution

$$K_1=\dfrac{1}{2}(1)(2v)^2=2v^2$$
$$K_2=\dfrac{1}{2}(2)(v)^2=v^2$$

$$\implies K_1 > K_2 $$