PHYS 1061 Lecture 8: 8

I believe I have the first part worked out:
U=mgh --> U=980 K+U=0 --> K= -980
-980=.5(20)(v^2) --> v=9.9 m/s
But I have no idea where to go on the second part.

Q= P E = mgh

(5000m³ * 1000/1m^3 kg)*(9.8 m/s^2)(50) <---water

S = Q/T = (2.45*10^9 J)/293K = 8360 KT/K

Q=mCΔT

Find the change in temperature in water

What is the force on a 1 C charge moving at 1 m/s perpendicular toa magnetic field with a strength of 1 tesla?

a) 0 N
b) 1 N
c) 2 N
d) 3 N