What is the energy of the photon emitted by a harmonic oscillator with stiffness 24 N/m and mass 6.8 × 10−26 kg when it drops from energy level 6 to energy level 3? Ephoton = ? J

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Asmall 21 kilogram canoe is floating downriver at a speed of 1 m/s. what is the canoe's kinetic energy?

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which value could describe the force of friction if polly could not move the box?