The picture below shows a toy car in the process of rolling down a ramp. At point X, the kinetic energy is 50 Joules (J), and the potential energy is 30 J.

What is the total energy in the system once the car reaches the bottom of the ramp?
A
20 J, because the energy in the system cannot change form but can be created and destroyed

B
80 J, because the energy in the system can change form but cannot be created or destroyed

C
30 J, because the potential energy is the only energy at the bottom of the ramp

D
50 J, because the kinetic energy is the only energy at the bottom of the ramp

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.