Work Energy and Power Test

Result

Work Energy and Power Test - 78

Score
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Rank
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Weekly Quiz Competition

Question 1
1 / -0

If water is flowing in a pipe at a height 4m from the ground then its potential
energy per unit volume is (Reference is taken at ground, $$ g=10 \mathrm{m} / \mathrm{s}^{2} ) $$

A
$$

20 \mathrm{kJ} / \mathrm{m}^{3}

$$

B
$$

10 \mathrm{kJ} / \mathrm{m}^{3}

$$

C
$$

40 \mathrm{kJ} / \mathrm{m}^{3}

$$

D
$$

30 \mathrm{kJ} / \mathrm{m}^{3}

$$
Question 2
1 / -0

Fig. shows a smooth curved track terminatingin a smooth horizontal part. A spring ofspring constant $$400\mathrm { Nm }$$ is attached at one end to the wedge fixed rigidly with the horizontal part. $$A\ 40 \mathrm { g }$$ mass is released from rest at a height of $$5\mathrm { m }$$ on the curved track. The maximum compression of the spring is $$\left( g = 10 \mathrm { m } / \mathrm { s } ^ { 2 } \right)$$

A
$$10\mathrm { cm }$$

B
$$5\mathrm { cm }$$

C
$$12\mathrm { cm }$$

D
$$8\mathrm { cm }$$

Solution
Question 3
1 / -0

A ball of mass 2 kg hits a floor with a speed of 4 m/s at an angle of $$ 60 ^o $$ with the normal.
If (e=1/2); then the change in the kinetic energy of the ball is

A
-6J

B
-12J

C
-9J

D
-3J

Solution
Question 4
1 / -0

A bucket tied at the end of a $$1.6m$$ long string is whirled in a vertical circle with a constant speed. What should be the minimum speed so that the water from the bucket does not spill when the bucket is at the highest position, (Take g=10m/s^2$$)

A
$$16m/s$$

B
$$6.25m/s$$

C
$$4m/s$$

D
$$2m/s$$

Solution
Question 5
1 / -0

A stone tied to a piece of string is shrilled in a vertical cirlce with uniform speed. In what position of the stone is the tension in the string greatest

A
in the highest position of stone

B
in the lowest position of stone

C
in the position when string is horizontal

D
is same for all positions of stone

Solution
Question 6
1 / -0

A force acts on a 2$$\mathrm { kg }$$ object so that itsposition is given as a function of time as $$x = 3 t ^ { 2 } + 5 .$$ What is the work done by thisforce in first 5 seconds?

A
$$960$$ $$J$$

B
$$950 J$$

C
$$850$$ $$J$$

D
$$875$$ $$J$$
Question 7
1 / -0

A body of mass 200 g moving on a test has final K.E. of 50 J after travelling a distance of 10 cm. Assuming 90% loss of energy due to friction. The initial speed of the body is

A
10 $$ms^{-1}$$

B
$$10\sqrt{50}ms^{-1}$$

C
$$5\sqrt{50}ms^{-1}$$

D
$$50\sqrt{50}ms^{-1}$$

Solution
Question 8
1 / -0

Potential energy v/s displacement curve for one dimensional conservative field is shown. Force at A and B is respectively -

A
Positive, Positive

B
Positive, Negative

C
Negative, Positive

D
Negative, Negative

Solution
Question 9
1 / -0

A circular road of radius 1000 m has banking angle $$45^{\circ}$$ The maximum safe speed $$\left ( in ms^{-1} \right )$$ of a car having a mass 2000 kg will be (if the coefficient of the friction between tyre and road is 0.5)

A
172

B
124

C
99

D
86

Solution
Question 10
1 / -0

An escalator is moving downwards with a uniform speed u. A man of mass 'm' is running upwards or it at a uniform speed v. If the height of the escalator is h, the work done by the man in going up the escalator is

A
zero

B
mgh

C
$$\frac{mghu}{(v-u)}$$

D
$$\frac{mghv}{(v-u)}$$

Solution