Auranium-235 sample starts with 200 atoms, and 700 million years later, there are 100 atoms. what is the half-life of uranium-235?
a. 350 million years
b. 235 years
c. 100 years
d. 700 million years

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?

What kind of waves require a medium to travel? question 6 options: light waves mechanical waves all waves need a medium to travel electromagnetic waves

Which of the following statements accurately describes the sign of the work done on the box by the force of the push? a. positive b. negative c. zero