Work

Q.

Is work a Vector or Scalar?

Q.

$5$ Examples of negative work done.

Q. The area under force vs displacement graph gives .

1. energy
2. work done
3. momentum
4. power

Q.

Is work a scalar or a vector quantity ?

Q. Why is work a scalar quantity?

Q.

The angle between force and displacement for maximum work should be

Q.

1kWh is equal to

1. 3.6×10⁶ MJ

2. 3.6×10⁵ MJ

3. 3.6×10² MJ

4. 3.6 MJ

Q. Question 11
What is the work done by the force of gravity on a satellite moving round the earth? Justify your answer.

Q.

A force $\overrightarrow{F}=5\hat{i}+6\hat{j}+4\hat{k}$acting on a body, produces displacement $\overrightarrow{S}=6\hat{i}-5\hat{k}$ . Work done by the force is

1. $10units$

2. $18units$

3. $11units$

4. $5units$

Q.

Work done by centripetal force is zero.

1. True
2. False

Q.

Is work done against gravity positive or negative? Explain.

Q.

What should be the angle between the direction of force and the direction of motion of a body so that the work done is zero?

Q.

In case of negative work, the angle between the force and displacement is :

(a) $0^{\circ }$

(b) ${45}^{\circ }$

(c) ${90}^{\circ }$

(d) ${180}^{\circ }$

Q. Question 12
Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.

Q. When a stone tied to a string is whirled in a circle, the work done on it by the string is:

1. Positive
2. Negative
3. Zero
4. Undefined

Q. A block of mass 2 kg is released from the top of an inclined smooth surface as shown in the figure. If spring constant of the spring is 150 N/m and the block comes to rest after compressing the spring by 1 m, then the distance travelled by the block before it comes to rest is

1. 6.5 m
2. 7.5 m
3. 2.5 m
4. 5 m

Q.

When a force of 10 n is applied continuously on a body and its displacement is 2m find out the magnitude of the work done by the force?

Q.

Question 12
A boy is moving on a straight road against a frictional force of 5 N. After travelling a distance of 1.5 km he forgot the correct path at a round about of radius 100 m. However, he moves on the circular path for one and a half cycle and then he moves forward up to 2.0 km. Calculate the work done by him.

Q.

One newton-metre is equal to one _____.

1. volt

2. hertz

3. joule

4. ampere

Q. Question 24
Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.
(a) How much work is done by the men in lifting the box?
(b) How much work do they do in just holding it?
(c) Why do they get tired while holding it? $(g=10m{s}^{-2})$

Q.

(a) Define the term 'work'. Write the formula for the work done on a body when a force acts on the body in the direction of its displacement. Give the meaning of each symbol which occurs in the formula.

(b) A person of mass 50 kg climbs a tower of height 72 metres. Calculate the work doen. (5 = 9.8 $m{s}^{-2}$)

Q.

The amount of work done depends on

1. Both force and displacement

2. displacement

3. time

4. force

Q.

A bullock is pulling a cart. The cart moves. There is a force on the cart and the cart has moved. Do you think that work is done in this situation?

Q.

What are the units of (a) work, and (b) energy ?

Q.

What is the relation between work and Energy?

Q.

Work done by friction can-never be positive.

1. True
2. False

Q.

Why is the work done on an object moving with uniform circular motion zero?

Q.

In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.

(a) How much work does he do in lifting one box ?

(b) How much energy is transferred when one box is lifted ?

(c) If the man lifts 4 boxes per minute, at what power is he working ? (g = 10 m $s^{-2}$)

Q.

No work is done by a force if it produces no motion on the body it is applied to.

1. True

2. False

Q.

What is Watt in physics?