1
JEE Main 2019 (Online) 10th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A particle which is experiencing a force, given by $$\overrightarrow F = 3\widehat i - 12\widehat j,$$ undergoes a displacement of $$\overrightarrow d = 4\overrightarrow i $$ particle had a kinetic energy of 3 J at the beginning of the displacement, what is its kinetic energy at the end of the displacement ?
A
9 J
B
10 J
C
12 J
D
15 J
2
JEE Main 2019 (Online) 10th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upward, as shown in figure. Work done by normal reaction on block in time is -

JEE Main 2019 (Online) 10th January Morning Slot Physics - Work Power & Energy Question 85 English
A
$${{m{g^2}{t^2}} \over 8}$$
B
$${{3m{g^2}{t^2}} \over 8}$$
C
$$-$$ $${{m{g^2}{t^2}} \over 8}$$
D
0
3
JEE Main 2019 (Online) 9th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A force acts on a 2 kg object so that its position is given as a function of time as x = 3t2 + 5. What is the work done by this force in first 5 seconds ?
A
850 J
B
950 J
C
875 J
D
900 J
4
JEE Main 2019 (Online) 9th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A block of mass m, lying on a smooth horizontal surface, is attached to a sring (of negligible mass) of spring constant k. The other end of the spring is fixed, as shown in the figure. The block is initially at rest in its equilibrium position. If now the block is pulled with a constant force F, the maximum speed of the block is :
JEE Main 2019 (Online) 9th January Morning Slot Physics - Work Power & Energy Question 87 English
A
$${{2F} \over {\sqrt {mk} }}$$
B
$${F \over {\pi \sqrt {mk} }}$$
C
$${{\pi F} \over {\sqrt {mk} }}$$
D
$${F \over {\sqrt {mk} }}$$
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