Physics question, ?

a cue ball with mass 170 g hits the stationary number 8 ball, which has mass 160 g. the cue ball and the 8 ball move with a speed of 0.2 m/s and 0.3 m/s respectively after the collision. what was the speed of the cue ball before the collision?

a) 0.2502 m/s
b) 0.4823 m/s
c) 0.5008 m/s
d) 0.5319 m/s

Describe how the fermi level changes with donor level, temperature and contact with p and n type semiconductors

Aparticle of mass m is projected with an initial velocity v0 in a direction making an angle α with the horizontal level ground as shown in the figure. the motion of the particle occurs under a uniform gravitational field g pointing downward. (a) write down the lagrangian of the system by using the cartesian coordinates (x, y). (b) is there any cyclic coordinate(s). if so, interpret it (them) physically. (c) find the euler-lagrange equations. find at least one constant of motion. (d) solve the differential equation in part (c) and obtain x and y coordinates of the projectile as a function of time. (e) construct the hamiltonian of the system, h, and write down the hamilton’s equations (canonical equations) of motion.

An open cart is moving along a straight frictionless horizontal track. when rain starts falling vertically into the cart, what happens to the speed of the cart?