Question 1 : A petrol engine has a work output of 96kJ per minute. What is the power I put if the engine efficiency is 20%? Question 2 : A crane lifts a load of 500kg to a height of 120m in 16s. If the power input is 45 000W, what is the efficiency of the motor used in the crane?

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?