JEE Main 2021 (Online) 1st September Evening Shift | Work Power & Energy Question 57 | Physics

JEE Main 2021 (Online) 1st September Evening Shift

MCQ (Single Correct Answer)

-1

A body of mass 'm' dropped from a height 'h' reaches the ground with a speed of 0.8$$\sqrt {gh} $$. The value of workdone by the air-friction is :

$$-$$0.68 mgh

mgh

1.64 mgh

0.64 mgh

JEE Main 2021 (Online) 31st August Evening Shift

MCQ (Single Correct Answer)

-1

A block moving horizontally on a smooth surface with a speed of 40 m/s splits into two parts with masses in the ratio of 1 : 2. If the smaller part moves at 60 m/s in the same direction, then the fractional change in kinetic energy is :-

$${{1 \over 3}}$$

$${{2 \over 3}}$$

$${{1 \over 8}}$$

$${{1 \over 4}}$$

JEE Main 2021 (Online) 27th July Evening Shift

MCQ (Single Correct Answer)

-1

Given below is the plot of a potential energy function U(x) for a system, in which a particle is in one dimensional motion, while a conservative force F(x) acts on it. Suppose that E_mech = 8 J, the incorrect statement for this system is :

JEE Main 2021 (Online) 27th July Evening Shift Physics - Work Power & Energy Question 64 English

JEE Main 2021 (Online) 27th July Evening Shift Physics - Work Power & Energy Question 64 English

[ where K.E. = kinetic energy ]

at x > x₄ K.E. is constant throughout the region.

at x < x₁, K.E. is smallest and the particle is moving at the slowest speed.

at x = x₂, K.E. is greatest and the particle is moving at the fastest speed.

at x = x₃, K.E. = 4 J.

JEE Main 2021 (Online) 27th July Evening Shift

MCQ (Single Correct Answer)

-1

An automobile of mass 'm' accelerates starting from origin and initially at rest, while the engine supplies constant power P. The position is given as a function of time by :

$${\left( {{{9P} \over {8m}}} \right)^{{1 \over 2}}}{t^{{3 \over 2}}}$$

$${\left( {{{8P} \over {9m}}} \right)^{{1 \over 2}}}{t^{{2 \over 3}}}$$

$${\left( {{{9m} \over {8P}}} \right)^{{1 \over 2}}}{t^{{3 \over 2}}}$$

$${\left( {{{8P} \over {9m}}} \right)^{{1 \over 2}}}{t^{{3 \over 2}}}$$

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