If the approximate energy of a photon present in an x-ray is 8.0 × 10-15 joules, what's the frequency of the x-ray? given: planck's constant is 6.63 × 10-34 joule·seconds.
(a)1.2 × 1014 hertz
(b)1.2 × 1019 hertz
(c)8.2 × 1018 hertz
(d)8.3 × 1019 hertz

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

Which car has the most kinetic energy? a. a car of mass 1000 kg with a speed of 3 m/s b. a car of mass 2000 kg with speed 7 m/s c. a car of mass 1000 kg with speed 7 m/s d. a car of mass 2000 kg with speed 3 m/s

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?