Atennis player hits a 1.45 kg tennis ball with a racket of mass 2.5 kg. if he hits the ball with a velocity of 7.5 m/s and then stops, what impulse did he imply on the ball? what is the ball’s velocity?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=

How does a circuit breaker protect a refrigerator? a. when the current is too high, a metal strip in the fuse melts and opens the circuit. b. when the resistance is too high , a re-settable which opens a circuit c. when the current is too high , a re-settable switch opens the circuit d. when the resistance is too high a metal strip in the fuse melts and opens the circuit