Physics #restart (Work, Energy & Power SET C - Medium)Contact Number: 8527521718Physics #restart (Work, Energy & Power SET C - Medium)Contact Number: 8527521718The kinetic energy of a body is increased by 21%. The percentage increase in the magnitude of linear momentum of the body will be:
1. 10%
2. 20%
3. Zero
4. 11.5%
The position of a particle \((x)\) varies with time \((t)\) as \(x = (t - 2)^2\), where \(x\) is in meters and \(t\) is in seconds. Calculate the work done during \(t=0\) to \(t=4\) s if the mass of the particle is \(100~\text{g}.\)
1. \(0.4~\text{J}\)
2. \(0.2~\text{J}\)
3. \(0.8~\text{J}\)
4. zero
A force \(F = -k(y\hat i +x\hat j)\) (where \(k\) is a positive constant) acts on a particle moving in the \(xy\text-\)plane. Starting from the origin, the particle is taken along the positive \(x\text-\)axis to the point \((a,0)\) and then parallel to the \(y\text-\)axis to the point \((a,a)\). The total work done by the force on the particle is:
1. \(-2ka^2\)
2. \(2ka^2\)
3. \(-ka^2\)
4. \(ka^2\)
A body of mass 'm' is released from the top of a fixed rough inclined plane as shown in the figure. If the frictional force has magnitude F, then the body will reach the bottom with a velocity:
| 1. | \(\sqrt{2 g h} \) | 2. | \(\sqrt{\frac{2 F h}{m}} \) |
| 3. | \(\sqrt{2 g h+\frac{2 F h}{m}} \) | 4. | \(\sqrt{2 g h-\frac{2 \sqrt{2} F h}{m}}\) |
What is the work done by the gravitational force on block \(A\) during the first \(2\) s after the blocks are released? (assume the pulley is light)
1. \( 240 ~\text J\)
2. \( 200 ~\text J\)
3. \(120 ~\text J\)
4. \( 24 ~\text J\)
If two springs, A and B are stretched by the same suspended weights, then the ratio of work done in stretching is equal to:
1. 1 : 2
2. 2 : 1
3. 1 : 1
4. 1 : 4
The potential energy of a system increases if work is done:
1. by the system against a conservative force.
2. by the system against a non-conservative force.
3. upon the system by a conservative force.
4. upon the system by a non-conservative force.
The potential energy of a \(1 ~\text{kg}\) particle free to move along the \(x\text-\)axis is given by \(U(x)=\left(\frac {x^4}{ 4}-\frac {x^2}{ 2}\right)~\text J.\) The total mechanical energy of the particle is \(2~\text J.\) Then the maximum speed (in \(\text{ms}^{-1}\)) will be:
1. \(\dfrac{3}{\sqrt{2}} \)
2. \(\sqrt{2}\)
3. \(\dfrac{1}{\sqrt{2}}\)
4. \(2\)
| 1. | \( \sqrt{\frac{m k}{2}} t^{-1 / 2} \) | 2. | \( \sqrt{m k} t^{-1 / 2} \) |
| 3. | \( \sqrt{2 m k} t^{-1 / 2} \) | 4. | \( \frac{1}{2} \sqrt{m k} t^{-1 / 2}\) |
A bullet of mass \(10\) g moving horizontal with a velocity of \(400\) m/s strikes a wood block of mass \(2\) kg which is suspended by light inextensible string of length \(5\) m. As a result, the centre of gravity of the block is found to rise a vertical distance of \(10\) cm. The speed of the bullet after it emerges horizontally from the block will be:
| 1. | \(100\) m/s | 2. | \(80\) m/s |
| 3. | \(120\) m/s | 4. | \(160\) m/s |
