Types of Work

Q.

Define Work Done By A Constant Force And Give Some Examples Of It

$$\begin{gathered} work=(\cos \tan tforce).\left(displacement\right) \\ orW=F.S=FS\cos \theta =(F\cos \theta )S=F\left(S\cos \theta \right) \end{gathered}$$

Q. What is work?

Q.

Work done on an object depends on the initial velocity of the object.

1. True

2. False

Q. When a porter moves on a railway platform, the work done on the load on his head is zero because the force applied on the load is in the upward direction but displacement it is in the horizontal direction. However the Porter is applying a force on the ground to move forwards, taking the load as a part of the Porter (since it touches him )the work done shouldn't be zero. Please explain the flaw in my concept in detail.

Q.

Work done by a coolie on the luggage on his head while carrying it on a horizontal road.

Q. How do you know that some entity is a form of energy?

Q.

In tug of war work done by the losing team is :

1. zero

2. positive

3. negative

4. none of these

Q.

When you are climbing stairs, work done by the weight is positive. (T or F)

1. True
2. False

Q.

When force applied is not in the direction of displacement of an object, is there any work done?

Why work is said to be negative when force is applied opposite to the direction of displacement?

Q. Choose the correct relation of work done where angle between force (F) and displacement(s) is $\theta$.

1. Work done is zero
2. Negative work done
3. Positive work done

Q.

Calculate the work done in pushing the card through distance of 15 against the force of friction equal to 250 Newton state the type of work done

Q.

Work done is zero when :

1. force causes displacement in its own direction.

2. force causes displacement in opposite direction.

3. force causes displacement in a perpendicular direction.

4. force causes displacement at an acute angle.

Q.

For what value of $\theta$ is work done

(a) maximum,

(b) zero?

Q.

Why is no work done, when a force acts at right angles to the direction of displacement ?

Q.

A car having a mass of 1000 kg and kinetic energy of 129600 J. The driver applies the brake when he suddenly sees an obstacle. The car comes to a halt after travelling 100 m distance without meeting an accident. Calculate the frictional force.

1. 1250 N

2. 1290 N

3. 1296 N

4. 626 N

Q. What is$\theta$ in $W=F\times s\times cos\theta$

Q. How is it that both weight and work done are represented by W​​​​​​?

Q.

Explain how force, energy and work are related?

Q.

If the angle between displacement and direction of force is ___________ then work done is maximum.

Q.

An 8N block slides down an incline, its initial speed is 7 ms^-1. The work done by the resultant force on the block is

1. 3 J

2. 6 J

3. Information insufficient

4. None of the above

Q. When 20 J of work was done on a gas, 40 J of heat energy was released. If the initial internal energy of the gas was 70 J. Then determine the final internal energy of the system.

1. 50 J
2. 60 J
3. 90 J
4. 10 J

Q.

There are two mutually perpendicular forces acting on an object. One force acts in the direction of motion of the object and the direction of other force is perpendicular to the motion. During this interval, the kinetic energy of the body changes from $25J$ to $100J$. The work done by the force acting perpendicular to the direction of the object is:

1. 0 J

2. 75 J

3. 25 J

4. 100 J

Q. $p-V$ diagram of an ideal gas is shown. The gas undergoes from initial state $A$ to final state $B$ such that initial and final volumes are same. Select the correct alternative for given process $AB$.

1. Work done by gas is positive.
2. Work done by gas is negative.
3. Temperature of gas increase continuously.
4. Process is isochoric.

Q. Work done by the normal reaction when a person climbs up the stairs is:

1. Positive
2. Negative
3. None of these
4. Zero

Q. By swimming forward in a swimming pool with butterfly stroke is a type of doing work.

1. True
2. False

Q. An ideal gas undergoes cyclic process $ABCDA$ as shown in given $PV$ diagram. The amount of work done by the gas is

1. $6P_0{V}_0$
2. $-2P_0{V}_0$
3. $+2P_0{V}_0$
4. $+4P_0{V}_0$

Q. A girl is carrying a school bag of $3kg$ mass on her back and moves $200m$ on a leveled road. The work done against the gravitational force will be ($g=10m/s^2$) :

1. $6J$
2. $Zero$
3. None of these
4. $6\times {10}^{3}J$
5. $0.6J$

Q.

State whether the work done in the following case is positive or negative.

Work done by a man in lifting a heavy box to the third floor of a building by means of a rope tied to the box.

Q.

An arrow fired from a bow attains a maximum height of $5m$ from the level it is released. If the mass of the arrow is $500grams$, work done by the bow on arrow is greater than which of the following? (Assume, $g=10m{s}^{-2}$)

1. $35J$

2. $20J$

3. $10J$

4. $30J$

Q. Find the external work done by the system in kcal, when $20$ kcal of heat is supplied to the system the increase in the internal energy is $8400J(J=4200J/kcal)$

1. $22kcal$
2. $18kcal$
3. $20kcal$
4. $19kcal$