A 0.175 kg softball is pitched horizontally at 26 m/s. the ball moves in the opposite direction at 38 m/s after it is hit by the bat. 1. what is the change in momentum?
2. what is the impulse delivered by the bat?
3. if the bat and ball are in contact for 0.80 seconds, what is the average force that the bat applies to the ball?

Space-time metric ds2= -dt2+at2dx2+bt2dy2+ct2dz2 (a)how does the area of a rectangle with vertices at ( x=0, y=0, z=0 ), (1,0,0 ), ( 0,1,0 ) and (1,1,0 ) changes with time? (b) if a photon moving in the x direction starts from the origin at t=1, when does it reach x=l? (ds=0 for the trajectory of a photon.) (c) the proper time for a particle is defined by cd=ds. what is the proper time for a particle to move along the trajectory ( x(t)=t, y(t)=0, z(t)=0 ) from t=0 to 1 ? what is the condition on the parameter a so that the velocity of the particle never exceeds the speed of light ?

Clothes dryer uses about 7 amps of current from a 240 volt line. how much power does it use?

What are the similarities & differences between a thermistor and a light dependent resistor in physics?