When did the fast food industry get its start

Ben(55 kg) is standing on very slippery ice when junior(25kg) bumps into him. junior was moving at a speed of 8m/s before the collision and ben and junior embrace after the collision. find the speed of ben and junior as they move across the ice after the collision .

Acamcorder has a power rating of 20 watts. if the output voltage from its battery is 9 volts, what current does it use?

What is the name of the perceived change in a sound wave’s frequency due to motion between the observer and the sound source?