HIGHLIGHT the correct a.) As the skater goes up the hill, his kinetic energy: increases / decreases / stays constant b.) As he goes up the hill, his potential energy: increases / decreases / stays constant c.) As he goes up the hill, his mechanical energy: increases / decreases / stays constant d.) As he goes down the hill, his kinetic energy: increases / decreases / stays constant e.) As he goes down the hill, his potential energy: increases / decreases / stays constant f.) As he goes down the hill, his mechanical energy: increases / decreases / stays constant

a) Kinetic energy decreases, b) Potential energy increases, c) Mechanical energy stays constant, d) Kinetic energy increases, e) Kinetic energy increases, f) Mechanical energy stays constant.  

Explanation:

a) Let suppose that the skater is a conservative system. If he goes up the hill, gravitational potential energy is increased at the expense of kinetic energy. In a nutshell, his kinetic energy decreases.

b) His potential energy increases.

c) Mechanical energy is the sum of gravitational potential and kinetic energies, since skater is conservative, then mechanical energy stays constant.

d) If he goes down the hill, his kinetic energy is increased at the expense of gravitational potential energy. In a nutshell, his kinetic energy increases.

e) His potential energy decreases.

f) Mechanical energy is the sum of gravitational potential and kinetic energies, since skater is conservative, then mechanical energy stays constant.

truck y has a greater velocity than truck x.

the best answer for these questions would be:

1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.