Work Done

Q.

The SI unit of work or energy is the joule. Explain why the work and energy have the same SI unit?

Q. A force of $1000N$ was applied to stop a car that was initially moving with a constant velocity. The car stopped after moving through $10m$. How much is the magnitude of work done by the force?

1. $1\times {10}^{4}J$
2. $2\times {10}^{4}J$
3. $3\times {10}^{4}J$
4. $4\times {10}^{4}J$

Q.

A man weighing 80 kg carries a weight of 40 kg on the top of a tower 60 m high. Find the work done by the man. Take $g=10m/s^2$.

Q. A cart with mass $20kg$ went $50m$ in a straight line on a plain and smooth road when a force of $2N$ was applied to it. How much work was done by the force?

1. $100J$
2. $400J$
3. $300J$
4. $200J$

Q. The CGS unit for energy is

Q.

A retarding force is applied to stop a motorcar. If the speed of the motorcar is doubled, how much more distance will it cover before stopping under the same retarding force?

Q. When a fast moving vehicle is suddenly stopped by force of $200N$, it came to rest after travelling $1m$. The magnitude of work done by the force is $200J$.

1. Due to opposing force of friction

2. Because action and reaction pair are never equal

Q. When a force of $5N$ is applied on a ball, the ball moves in the direction of applied force for $2m$ under it's influence. Work done on the ball by the force is _________.

1. $10J$

2. $5J$

3. $1J$

4. $15J$

Q. An ant drags a piece of a sweet from origin $(0,0)$ to $(3,4)$ in the co-ordinate axes. What is the work done by the ant if it applies a force of $1N$ and takes the shortest path?
$(1\text{unit}=1\text{metre}$)

1. 1 J

2. 3 J

3. 5 J

4. 7 J

Q. Work done is measured as a product of force and. It is aquantity.

1. displacement
2. distance
3. speed
4. scalar
5. vector

Q. A body of mass 100g is rotating in a circular path of radius 'r' with constant speed.The work done in one complete revolution is:

1. (100r) J
2. $\left(\frac{r}{100}\right)J$
3. $\left(\frac{100}{r}\right)J$
4. $zero$

Q. A $4kg$ cart starts moving up an incline of ${45}^o$ with a speed of $8m/s$ and comes to rest after moving up $2m$ along the incline. Find the total work done by all forces on the cart.

1. $8J$
2. $0J$
3. $40\sqrt{2}J$
4. $40\sqrt{3}J$

Q. Units of work done is ________.

1. $kgm{s}^{-2}$
2. $kg{m}^2{s}^{-2}$
3. $kg{m}^2{s}^{-1}$
4. $kgm{s}^{-1}$

Q. The work done can be more for the same displacement when ___.

1. same force is applied
2. no force is applied
3. force applied is more
4. force applied is less

Q. And maam how to convert per cm to joule or viceversa

Q.

A man rowing a boat upstream is at rest with respect to a bank is he doing any work?

Q. The displacement of a particle of mass $10$g moving in one dimension under the action of a constant force $5$N is related with time as $t=\sqrt{x}+2$, where x is in metre and 't' is in second. The work done by the force in first $5$s will be.

1. $45$J
2. $80$J
3. $20$J
4. $35$J