575 - Physics Questions Answers

A sleeping cat and a sleeping dog are initially at a distance 'l' metres. As soon as the dog wakes up, the cat runs in the horizontal direction with constant velocity of u m/s. Immediately the dog chases the cat with constant speed of v m/s. Initially the dog was facing the north direction towards cat. The cat starts running in the east direction. Assuming the dog aims at the cat with constant speed v m/s, find the time after which the dog chases the cat.

Sir, can third law of Newton  be derived from second law??

actually as we all know that second law is real law so first  & second law can be derived,  but on the other side it is written that they are THE LAWS ARE INDEPENDENT THUS CAN'T BE DERIVED FROM ANY OTHER LAW (acc to HC Verma)

sir sometime ans is yes while sometime no , in different books different ans , i consulted this query to many  other teachers also but some favours while some teachers not , so what you suggest?

is this depends upon questn setting person

a particle moving in a straight line with an initial velocity u is subjected to a constant acceleration,a. Show that the distance traveled by the particle in the nth second is; Sn=u+a(n-0.5)

The temperature of a perfect black body

is 1000k and its area

is 0.1m² . the heat radiated by it in 1 minute in joule is

Time of flight of a projectile thrown from ground is 8√5 s. It will rise up to a height of.........

A resistor of 10kΩ having tolerance 10 % is connected in series with another resistor of 20 kΩ having tolerance 20 %. The tolerance of the combination will be approximately.

A projectile is projected with velocity u= ai+bj from ground if acceleration due ti gravity is g, then the change in velocity of the projectile in second of projection is

A shell at rest at large height explodes into two parts which move horizontally with speeds v¹ and v². After what time their instantaneous velocities are perpendicular?

A particle moving in uniform circular motion undergoes an angular displacement α (less then 360°) from point P and Q. Then angle between average velocity from P to Q and velocity at Q is........

A particle moves in the plane xy with velocity v = ai + bxj, where i and j are the unit vectors of the x and y axes, and a and b are constants. At the initial moment of time the particle was located at the point x = y = 0. Find: 
(a) the equation of the particle's trajectory y(x); 
(b) the curvature radius of trajectory as a function of x.