# Relative velocity of a thrown object w.r.t. ground [closed]

An old-fashioned coke bottle is thrown straight out from the right side of a car at 10 m/s. The car is moving at 80 miles per hour. What is the speed of the bottle relative to the ground (in m/s)?

I've converted the speed of the car, and it turned out to be 35.76 m/s. But I'm not sure how to find the speed of the bottle relative to the ground. Please help.

Would the speed of the bottle be equal to the speed of the car added to the velocity with which its thrown? (35.76 m/s + 10 m/s = 45.76 m/s)

Edit: Thank you! The answer would then turn out to be 37.13 m/s, right?

## closed as off-topic by Kyle Kanos, Aaron Stevens, StephenG, user191954, John RennieFeb 24 at 10:06

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – Kyle Kanos, Aaron Stevens, StephenG, Community, John Rennie
If this question can be reworded to fit the rules in the help center, please edit the question.

## 1 Answer

By saying 'side of the car' usually means that the object has been thrown perpendicular (unless given a specific angle), so you have to calculate the absolute quantity of the resulting velocity vector that is made by two perpendicular vectors V1 and V2. In other words you need to use the Pythagor's theorem (since the angle is 90 degree) and find out the third value from the two given.