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

Concept Questions :-

Gravitational Potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

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

Concept Questions :-

Elastic potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The potential energy of a certain spring when stretched through a distance ‘S’ is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance ‘S’ will be:

(1) 30

(2) 40

(3) 10

(4) 20

Concept Questions :-

Elastic potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A position dependent force $F=7-2x+3{x}^{2}\text{\hspace{0.17em}}newton$ acts on a small body of mass 2 kg and displaces it from x = 0 to x = 5 m. The work done in joules is:

(1) 70

(2) 270

(3) 35

(4) 135

Concept Questions :-

Work done by variable force
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A body of mass 3 kg is under a force, which causes a displacement in it, given by $S=\frac{{t}^{3}}{3}$ (in m). Find the work done by the force in first 2 seconds:

(1) 2 J

(2) 3.8 J

(3) 5.2 J

(4) 24 J

Concept Questions :-

Work done by variable force
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A spring of force constant 800 N/m has an extension of 5cm. The work done in extending it from 5cm to 15 cm is:

(1) 16 J

(2) 8 J

(3) 32 J

(4) 24 J

Concept Questions :-

Elastic potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A spring of spring constant 5 × 103 N/m is stretched initially by 5cm from the unstretched position. Then the work required to stretch it further by another 5 cm is

(1) 6.25 N-m

(2) 12.50 N-m

(3) 18.75 N-m

(4) 25.00 N-m

Concept Questions :-

Elastic potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A mass of 0.5kg moving with a speed of 1.5 m/s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k = 50 N/m. The maximum compression of the spring would be

(1) 0.15 m

(2) 0.12 m

(3) 1.5 m

(4) 0.5 m

Concept Questions :-

Elastic potential energy
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to

(1) x2

(2) ex

(3) x

(4) loge x

Concept Questions :-

Concept of work
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

If a long spring is stretched by 0.02 m, its potential energy is U. If the spring is stretched by 0.1 m, then its potential energy will be

(1) $\frac{U}{5}$

(2) U

(3) 5U

(4) 25U

Concept Questions :-

Elastic potential energy