The work output of a lever used to lift books is 30 Joules and the work input is 60 Joules. What is the efficiency of this lever?

Spend time observing or thinking about events that involve matter and energy. which events can you explain? which events can’t you explain?

The density of a liquid could be found by using

Red light strikes a metal surface and electrons are ejected. if violet light is now used with a 10% greater intensity, what will happen to the ejection rate (number of ejected electrons per second) and the maximum energy of the electrons? a) greater ejection rate; same maximum energyb) same ejection rate; greater maximum energyc) greater ejection rate; greater maximum energyd) same ejection rate; same maximum energye) none of the above answers are correct