For problem number 4:
It says it is moving 10% of the speed of light. The speed of light is 3*10^8 m/s.
So:
KE = 0.5mv^2 = 0.5*(1.67*10^-27kg)(3*10^8*0.1)^2
KE = 7.515*10^-13 J
Problem 5:
W = ΔKE
Since it is initially at rest, we can simplify W = KE. KE = 0.5mv^2
3.4*10^-16J = 0.5(9.11*10^-31)v^2
v = 27320916.74 m/s
Problem 6:
mgh = 0.5mv^2
(0.1kg)*(10m/s^2)*(16m) = 0.5(0.1kg)v^2
v = 17.8885m/2
Did this really quickly, so might not be accurate!