Al was his sister, betsy, slide down the slide at the park. she held on to the sides of the slide the whole way down. when they got to the bottom, she noticed that her hands were warm. what caused betsy's hands to be warm?

The answer to your question is Friction

Explanation:

As is mentioned in the question, Betsy held on to the sides of the slide the whole way down, that means that her hands were rubbing the slide and this process causes a force called friction. And Friction is perceived as heat.

The definition of friction is: Friction is the resistance to motion of one object moving relative to another.

In your question her hands create a resistance to motion.

this means that the temperature of both substances will be equal

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j