1
JEE Main 2022 (Online) 24th June Morning Shift
+4
-1

A particle experiences a variable force $$\overrightarrow F = \left( {4x\widehat i + 3{y^2}\widehat j} \right)$$ in a horizontal x-y plane. Assume distance in meters and force is newton. If the particle moves from point (1, 2) to point (2, 3) in the x-y plane, then Kinetic Energy changes by :

A
50.0 J
B
12.5 J
C
25.0 J
D
0 J
2
JEE Main 2021 (Online) 1st September Evening Shift
+4
-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 :
A
$$-$$0.68 mgh
B
mgh
C
1.64 mgh
D
0.64 mgh
3
JEE Main 2021 (Online) 31st August Evening Shift
+4
-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 :-
A
$${{1 \over 3}}$$
B
$${{2 \over 3}}$$
C
$${{1 \over 8}}$$
D
$${{1 \over 4}}$$
4
JEE Main 2021 (Online) 27th July Evening Shift
+4
-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 Emech = 8 J, the incorrect statement for this system is :

[ where K.E. = kinetic energy ]
A
at x > x4 K.E. is constant throughout the region.
B
at x < x1, K.E. is smallest and the particle is moving at the slowest speed.
C
at x = x2, K.E. is greatest and the particle is moving at the fastest speed.
D
at x = x3, K.E. = 4 J.
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