All vehicles are required to stop within how many feet of a railroad crossing when a train is approaching

The sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

This is important. 1. which of the following is an si base unit for measuring length? (2 points) inch gram meter mole 2. which of the following units for distance is an si unit? (2 points) centimeter foot inch yard 3. which of the following tools should a scientist use to measure an object in meters? (2 points) electronic balance pan balance tape measure thermometer

What kind of simple machine is a catapult?