Mechanics | Relativity Answers

I read that rest mass(Mo) of photon is zero.
Einstein's relativistic mass m=Mo/[1-(v/c)^2]
if Mo=0 then m=0
but also velocity of photon is c then m=0/0 (interderminate)
can anybody explain please

A 3oo kg sailboat accelerates at 0.5 m/s2 at angle 25 degrees N of E, find the magnitude and direction of the force responsible for this acceleration

1)an object is placed on the surface of a smooth inclined plane of inclination θ.it takes time t to reach the bottom. if the same object is allowed to slide down inclined plane on inclination θ,it takes time nt to reach the bottom where n is a number greater than 1. what is coefficient?
2)The force required to just move a body up the inclined plane is doublethe force required to justprevent the body from sliding down the plane.the coefficient of friction is μ.find the inclination θ of the plane
3)a particle inside a hollow sphere of radius r, having coeffient of friction(1/√3), upto what height can particle be at rest?

a small block starts sliding down an inclined plane forming an angle with the horizontal the coefficient of friction depends on the distance covered from rest along as ax where a=constant. find distance covered by the block down the plane, till it stops sliding,and its max velocity during this journey

if a strain leaves station A, take 2ms squared to get to 36ms then travels for 90 seconds and then decelerates at 3ms squared to stop at station B. What was the total distance traveled? How long did it take the train from station A to station B?

Establish the differential equation for damped harmonic oscillator and obtain its solution.
Show that the damped oscillator will exhibit non-oscillatory behavior if the damping is
heavy.

Write the equation of motion of a forced weakly damped harmonic oscillator and explain
the physical significance of each term. Obtain the steady-state solution of this equation.

An ambulance siren has a fundamental frequency of 261 Hz .The ambulance is headed
towards an accident site with a speed of 100km/h .Two police officers on separate
motor cycles head for the same accident site: one follows the ambulance with a speed of 90km/h
and the other approaches the accident site from the other direction with a speed of 90 km/h .
What frequency does the ambulance siren has for each of the police
officers? Take the speed of sound equal to 340m/s .

you push your physics book 1.50m long a horizontal table top with a horizontal force of 2.40N .the opposing force of friction is 0.600N.

a)how much work does your 2.40N force do on the book?

b)what is the work done in the book by the friction force?

A student conducted an experiment to measure the acceleration due to gravity,g, of a simple pendulum. The data obtained are tabulated:
LENGTH O THREAD,L/M 0.35 0.65 1.00 1.45 1.95
TIME FOR 20 24.1 32.4 40.1 47.5 56.3
OSCILLATIONS,T/S
Given that the relation between the periodic time,T,=2 pi square root of L/G, find the value of g using a graphical approach.