# A force acts on a 30 gm particle in such a way that the position of the particle as a function of time is given by $x=3t-4{t}^{2}+{t}^{3}$, where x is in metres and t is in seconds. The work done during the first 4 seconds is  (1) 5.28 J (2) 450 mJ (3) 490 mJ (4) 530 mJ

Subtopic:  Work Done by Variable Force |
61%
From NCERT
PMT - 1998
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The minimum work done in pulling up a block of wood weighing $$2$$ kN for a length of $$10$$ m on a smooth plane inclined at an angle of $$15^\circ$$ with the horizontal is (given: $$\mathrm{sin}15^\circ=0.2588)$$:
1. $$4.36$$ kJ
2. $$5.17$$ kJ
3. $$8.91$$ kJ
4. $$9.82$$ kJ

Subtopic:  Work done by constant force |
79%
From NCERT
PMT - 2003
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A body of mass 6kg is under a force which causes displacement in it given by $S=\frac{{t}^{2}}{4}$ metres where t is time. The work done by the force in 2 seconds is-

(1) 12 J

(2) 9 J

(3) 6 J

(4) 3 J

Subtopic:  Work Done by Variable Force |
72%
From NCERT
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A particle moves from position ${\stackrel{\to }{r}}_{1}=\text{\hspace{0.17em}}3\stackrel{^}{i}+2\stackrel{^}{j}-6\stackrel{^}{k}$ to position ${\stackrel{\to }{r}}_{2}=14\stackrel{^}{i}+13\stackrel{^}{j}+9\stackrel{^}{k}$ under the action of force $4\stackrel{^}{i}+\stackrel{^}{j}+3\stackrel{^}{k}\text{\hspace{0.17em}}N.$ The work done will be

(1) 100 J

(2) 50 J

(3) 200 J

(4) 75 J

Subtopic:  Concept of Work | Work Done by Variable Force | Power |
82%
From NCERT
PMT - 2002
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A uniform chain of length 2m is kept on a table such that a length of 60cm hangs freely from the edge of the table. The total mass of the chain is 4kg. What is the work done in pulling the entire chain on the table?

(1) 7.2 J

(2) 3.6 J

(3) 120 J

(4) 1200 J

Subtopic:  Gravitational Potential Energy |
67%
From NCERT
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A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that

(1) Its velocity is constant

(2) Its acceleration is constant

(3) Its kinetic energy is constant

(4) It moves in a straight line

Subtopic:  Work done by constant force |
57%
From NCERT
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Two bodies of masses 1 kg and 5 kg are dropped gently from the top of a tower. At a point 20 cm from the ground, both the bodies will have the same

(1) Momentum

(2) Kinetic energy

(3) Velocity

(4) Total energy

Subtopic:  Concept of Work |
61%
From NCERT
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A particle moves under the effect of a force F = Cx from x = 0 to x = x1. The work done in the process is

(1) $C{x}_{1}^{2}$

(2) $\frac{1}{2}C{x}_{1}^{2}$

(3) $C{x}_{1}$

(4) Zero

Subtopic:  Work Done by Variable Force |
83%
From NCERT
PMT - 1982
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A cord is used to lower vertically a block of mass M by a distance d with constant downward acceleration $\frac{g}{4}$. Work done by the cord on the block is

(1) $Mg\frac{d}{4}$

(2) $3Mg\frac{d}{4}$

(3) $-3Mg\frac{d}{4}$

(4) Mgd

Subtopic:  Gravitational Potential Energy |
59%
From NCERT
PMT - 1972
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Two springs have their force constant as k1 and ${k}_{2}\left({k}_{1}>{k}_{2}\right)$. When they are stretched by the same force

(1) No work is done in case of both the springs

(2) Equal work is done in case of both the springs

(3) More work is done in case of second spring

(4) More work is done in case of first spring

Subtopic:  Elastic Potential Energy |
65%
From NCERT
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