WBJEE · Physics · Laws of Motion
A block of mass \(m(=0.1 \mathrm{kg})\) is hanging over a frictionless light fixed pulley by an inextensible string of negligible mass. The other end of the string is pulled by a constant force \(F\) in the vertically downward direction. The linear momentum of the block increases by \(2 \mathrm{kgms}^{-1}\) in \(1 \mathrm{s}\) after the block starts from rest. Then, (given \(g=10 \mathrm{ms}^{-2}\) ) 
- A The tension in the string is \(F\)
- B The tension in the string is \(3 \mathrm{N}\)
- C The work done by the tension on the block is \(20 \mathrm{J}\) during this 1 s
- D The work done against the force of gravity is \(10 \mathrm{J}\)
Answer & Solution
Correct Answer
(D) The work done against the force of gravity is \(10 \mathrm{J}\)
Step-by-step Solution
Detailed explanation
The free body diagram \(\Rightarrow \quad F=2+m g=3 N\) also, \(a=\frac{\text { unbalanced force }}{\text { mass }}=\frac{2}{0.1}=20 \mathrm{m} / \mathrm{s}^{2}\) \(S=\frac{1}{2} a t^{2}=\frac{1}{2} \times 20 \times 1=10 \mathrm{m}\) Honce, work done by tension…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- The following figure shows the variation of potential energy V(x) of a particle with distance x. The particle has
WBJEE 2024 Easy - Average distance of the Earth from the Sun is \(L_{1}\) : If one year of the Earth \(=D\) days, one year of another planet whose average distance from the Sun is \(L_{2}\) will beWBJEE 2012 Easy
- A spring of force constant \(\mathrm{k}\) is cut into two equal halves. The force constant of each half isWBJEE 2009 Medium
- A particle is projected at \(60^{\circ}\) to the horizontal with a kinetic energy \(\mathrm{K}\). The kinetic energy at the highest point isWBJEE 2009 Hard
- The value of ' \(\lambda\) ' for which the two vectors \(\vec{a}=5 \hat{i}+\lambda \hat{j}+\hat{k}\) and \(\vec{b}=\hat{i}-2 \hat{j}+\hat{k}\) are perpendicular to each other isWBJEE 2010 Easy
- A planet moves around the sun in an elliptical orbit with the sun at one of its foci. The physical quantity associated with the motion of the planet that remains constant with time isWBJEE 2013 Medium
More PYQs from WBJEE
- Let \(g(x)=\int_{x}^{2 x} \frac{f(t)}{t} d t\) where \(x>0\) and \(f\) be continuous function and \(f(2 x)=f(x)\), thenWBJEE 2021 Easy
- \(\begin{array}{llll}\text { 3. The sum } & \text { of } & \text { the } & \text { series }\end{array}\) \(1+\frac{1}{2}{ }^{n} C_{1}+\frac{1}{3}{ }^{n} C_{2}+\quad+\frac{1}{n+1}{ }^{n} C_{n}\) is equal toWBJEE 2012 Hard
- How and why does the density of liquid water change on prolonged electrolysis?WBJEE 2020 Easy
- If \(\mathrm{C}\) is the reflecton of \(\mathrm{A}(2,4)\) in \(\mathrm{x}\)-axis and \(\mathrm{B}\) is the reflection of \(\mathrm{C}\) in \(\mathrm{y}\)-axis, then \(|\mathrm{AB}|\) isWBJEE 2009 Easy
- The shape of \(XeF_{5}^{-}\) will beWBJEE 2017 Easy
- From a collection of 20 consecutive natural numbers, four are selected such that they are not consecutive. The number of such selections isWBJEE 2018 Medium