What time is it? pls answer

Crowbar of 5 metre is used to lift an object of 800 metre if the effort arm is 200cm calculate the force applied

What are two different ways you could find the value of a? explain these methods.

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?