The answer is False. Permafrost does not thaws briefly in the summer since Permafrost is all year round. As global temperature rise, the amount that frozen soil that melts is increasing. With warmer temperature, snow and ice that used to reflect sunlight is disappearing. Thus, the newly exposed soil absorbs heat from the sunlight, and encourages melting.
Momentum equation is
change in momentum = mass•initial velocity•final velocity
so....
p=700(15) because your initial is 30, and your final in 15, so you subtract! hope that helped!
the friction if sliding is greater than rolling
More expensive & probably less complicated
Answer:

Explanation:
F = Force = 
m = Mass of proton = 
t = Time taken = 
Acceleration is given by


The velocity of the proton is 