A 40-kg girl is running through the supermarket and jumps onto a stationary shopping cart full of groceries that has a total
mass of 80-kg. They roll away together at a speed of 7 m/s.
How fast must she have been running before the collision?
m/s

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells? burning fossil fuels contributes to climate change. burning fossil fuels takes place inside expensive fuel cells. fossil fuels aren't widely available, but pure hydrogen is. fossil fuels are nonrenewable.

In which of the following cases is work being done on an object? question 2 options: pushing against a locked door carrying a box down a corridor pulling a trailer up a hill suspending a heavy weight with a strong

How do we measure or think of speed in the united states?