Work Done on & by the Object

Q.

A uniform chain of length $L$ and mass $M$ is lying on a smooth table and one-third of its length is hanging vertically down over the edge of the table. If $g$ is the acceleration due to gravity, the work required to pull the hanging part onto the table is

Q.

A given object takes n times more time to slide down ${45}^{\circ }$ rough inclined plane as it takes to slide down a perfectly smooth ${45}^{\circ }$ incline. The coefficient of kinetic friction between the object and the incline is

1. 

2. 

3. 

4. 

Q. 61.The accelaration of the particle moving rectilinearly varies with displacement as a=-4x. At x=4 m and t=0, particle is at rest. Select the correct alternative A)The maximum speed of the particle is 8 m/s B)The distance travelled by the particle in the first second is 20 m C)The velocity-accelaration graph of the particle is an ellipse D)The kinetic energy-displacement graph of the particle is a parabola

Q. 53.The position x of a particle moving along x axis at time (t) is given by the equation t =( under root x) +2, where x is in meters and t in seconds. Find the work done by the force in the first four sec

Q. the slope of kinetic energy vs position graph gives us the time rate of change of

Q. force versus displacement curve is shown in the diagram. the work done by the force at the end of displacement 40m is

Q. A block of mass $m$ is kept on a platform which starts from rest with constant acceleration $\frac{g}{2}$ upwards as shown in the figure. Work done by the normal reaction on the block in time $t$ is:

1. $\frac{m{g}^2{t}^2}{8}$
2. $\frac{3m{g}^2{t}^2}{8}$
3. \N
4. $-\frac{m{g}^2{t}^2}{8}$

Q. A force of $5\text{N}$, making an angle $\theta$ with the horizontal, acting on an object and displaces it by $0.4\text{m}$ along the horizontal direction. If the work done by the force is $1\text{J}$, then the horizontal component of the force is

1. $1.5\text{N}$
2. $2.5\text{N}$
3. $3.5\text{N}$
4. $4.5\text{N}$

Q. In the figure as shown two blocks are connected by a string over a pulley.

Calculate the total work done by tension force on the system for $1\text{m}$ distance covered.

1. $\frac{80}{3}\text{N}$
2. $-\frac{80}{3}\text{N}$
3. Zero
4. None

Q. In the shown pulley-block system, strings are light. Pulleys are massless and smooth and system is released from rest. In $0.6$ second, what is the work done by gravity on $20\text{kg}$ and $10\text{kg}$ block respectively ?
Take $[g=10{\text{m/s}}^2]$

1. $120\text{J};30\text{J}$
2. $30\text{J};120\text{J}$
3. $240\text{J};-60\text{J}$
4. $-240\text{J};60\text{J}$

Q. A body constrained to move along the $z$-axis of a co-ordinate system is subjected to a constant force $\overrightarrow{F}=(-\hat{i}+2\hat{j}+3\hat{k})\text{N}$. What is the work done by the force in moving the body over a distance of $4\text{m}$ along the $z$-axis?

1. $6\text{J}$
2. $8\text{J}$
3. $16\text{J}$
4. $12\text{J}$

Q. Figure gives the acceleration of a $2.0\text{kg}$ body as it moves from rest along $x-$ axis, while a variable force acts on it from $x=0\text{m}$ to $x=9\text{m}$.
The work done by the force on the body when it reaches $x=4\text{m}$ and $x=7\text{m}$ is

1. $21\text{J}$ and $33\text{J}$ respectively
2. $21\text{J}$ and $15\text{J}$ respectively
3. $42\text{J}$ and $60\text{J}$ respectively
4. $42\text{J}$ and $30\text{J}$ respectively

Q. In the shown pulley-block system, strings are light. Pulleys are massless and smooth and system is released from rest. In $0.6$ second, what is the work done by gravity on $20\text{kg}$ and $10\text{kg}$ block respectively ?
Take $[g=10{\text{m/s}}^2]$

1. $120\text{J};30\text{J}$
2. $30\text{J};120\text{J}$
3. $240\text{J};-60\text{J}$
4. $-240\text{J};60\text{J}$

Q. On a certain planet, a stone weighing $2\text{kg}$ is thrown vertically downwards with a velocity of $5\text{m/s}$ from a height of $30\text{m}$. It took $4\text{s}$ to reach the ground. Calculate the work done by gravity.

1. $-75\text{J}$
2. $60\text{J}$
3. $-60\text{J}$
4. $75\text{J}$

Q. A string is used to pull a block of mass $m$ vertically up by a distance $h$ at a constant acceleration $\frac{g}{4}$. The work done by the tension in the string is

1. $+\frac{3}{4}mgh$
2. $-\frac{1}{4}mgh$
3. $+\frac{5}{4}mgh$
4. $+mgh$

Q. Force - displacement curve for a body in one dimensional motion is as shown in the figure.

Work done by the force in displacing the body from displacment zero to $6\text{m}$ is given by

1. zero
2. $10\text{J}$
3. $20\text{J}$
4. $60\text{J}$

Q. A string is used to pull a block of mass $m$ vertically up by a distance $h$ at a constant acceleration $\frac{g}{4}$. The work done by the tension in the string is

1. $+\frac{3}{4}mgh$
2. $-\frac{1}{4}mgh$
3. $+\frac{5}{4}mgh$
4. $+mgh$

Q. The position x of a particle moving along x -axis is given by the equation t=x +2 , where x is in metres and tin seconds .find the work done by the force in first four seconds.