A child pushes a toy car down a hill. After 5 seconds, the car has a kinetic energy of 115 J and a gravitational potential energy of 30 J. What is the car’s mechanical energy at that time?

A) 3.9 J
B) 85 J
C) 115 J
D) 145 J

D) 145 J

Explanation:

Mechanical energy = kinetic energy + potential energy

ME = KE + PE

ME = 115 J + 30 J

ME = 145 J

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.