575 - Physics Questions Answers

Physics >> Mechanics part 1 >> Kinematics IIT JEE

Two boys enter a running escalator at the ground floor of a shopping mall . The first boy repeatedly follows a cycle of p1=1 step up and then q1=2 steps down whereas the second boy repeatedly follows a cycle of p2=2 steps up and then q2=1 step down. Both of them move relative to escalator with a speed v=50cm/s . If the boys take t1=250s and t2=50s respectively to reach the first floor in complete number of cycles, how fast is the escalator running ?

Asked By: JATIN KUMAR

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Joshi sir comment

$l e t u a n d v a r e t h e s p e e d s o f b o y a n d e s c a l a t o r a c c o r d i n g t o g i v e n c o n d i t i o n [1 (u + v) T - 2 (u - v) T] n_{1} = [2 (u + v) T - 1 (u - v) T] n_{2} \Rightarrow [1 (u + v) - 2 (u - v)] T n_{1} = [2 (u + v) - 1 (u - v)] T n_{2} G i v e n t h a t T n_{1} = 250 a n d T n_{2} = 50 \Rightarrow [1 (u + v) - 2 (u - v)] 250 = [2 (u + v) - 1 (u - v)] 50 n o w s o l v e i t f o r v, u i s g i v e n$

Physics >> Mechanics part 1 >> Kinematics IIT JEE

A particle projected from the ground passes two points , which are at height 12m and 18m above the ground and a distance d=10m apart . What could be the minimum speed of projection. Acceleration due to gravity is g=10m/s^2 .

Asked By: JATIN KUMAR

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Joshi sir comment

Physics >> Mechanics part 1 >> Kinematics IIT JEE

Sir along with the written question, can you also calculate the velocity of the midpoint of CD( marked in green) under the same conditions as in question? Thank you

Asked By: DARIUS

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Solution by Joshi sir

Physics >> Mechanics part 1 >> Rotational mechanics IIT JEE

Asked By: PRIYANSHU SINGH

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Joshi sir comment

Physics >> Magnetism >> Electromagnetic Induction IIT JEE

Asked By: AYUSH PAINE

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Joshi sir comment

Physics >> Mechanics part 1 >> Kinematics IIT JEE

Asked By: FURQAAN

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Joshi sir comment

Physics >> Magnetism >> Electromagnetic Induction IIT JEE

SIR ANSWER IS given as C could u pls explain?

Asked By: AYUSH PAINE

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Joshi sir comment

Physics >> Electricity >> Electric Field and Potential IIT JEE

Asked By: KRISHAV RAJ SINGH

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Solution by Joshi sir

$\frac{k q_{1} q_{2}}{{l_{3}}^{2}} = \frac{k q_{2} q_{3}}{{l_{1}}^{2}} = \frac{k q_{3} q_{1}}{{l_{2}}^{2}} l_{1} + l_{2} + l_{3} = L f r o m t h e s e 2 e q u a t i o n s \frac{L \frac{1}{\sqrt{q_{1}}}}{\frac{1}{\sqrt{q_{1}}} + \frac{1}{\sqrt{q_{2}}} + \frac{1}{\sqrt{q_{3}}}}, \frac{L \frac{1}{\sqrt{q_{2}}}}{\frac{1}{\sqrt{q_{1}}} + \frac{1}{\sqrt{q_{2}}} + \frac{1}{\sqrt{q_{3}}}}, \frac{L \frac{1}{\sqrt{q_{3}}}}{\frac{1}{\sqrt{q_{1}}} + \frac{1}{\sqrt{q_{2}}} + \frac{1}{\sqrt{q_{3}}}}$

Physics >> Magnetism >> Alternating Current IIT JEE

SIR the answer is given only D could you pls explain

Asked By: AYUSH PAINE

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Joshi sir comment

$X_{C} = 50 Ω a n d X_{L} = 100 Ω a r e i n p a r a l l e l . R e s u l \tan t i s 100 Ω c a p a c i \tan c e . N o w 100 Ω c a p a c i \tan c e a n d 100 Ω i n d u c \tan c e g i v e r e a c \tan c e 0 Ω a n d r e s i s \tan c e i s 100 Ω . S o o n l y o p t i o n D i s c o r r e c t .$

Physics >> Mechanics part 1 >> Rotational mechanics IIT JEE

A rotating ball hits a rough horizontal plane with a vertical velocity $v$ and angular velocity $w$ . Given that the coefficient of friction is $u$ and the vertical component of the velocity after the collision is $v / 2$ , find:

a) the angular velocity after collision;

b) the impulsive ground reaction during the collision

Asked By: UDDESH KUMAR SABAT

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Joshi sir comment

on applying momentum impulse theorem along vertical

-mv+Ndt = mv/2 (1)

by angular momentum angular impulse theorem

$2 m ω r^{2} / 5 - μ N d t r = 2 m ω^{,} r^{2} / 5 (2)$ By eq. (2) get angular velocity.

impulsive ground reaction = $\sqrt{{(N d t)}^{2} + {(μ N d t)}^{2}}$ by using eq. (1), solve it

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