What causes interstellar dust and gas to start to contract and form a protostar?

1) the shockwave from a supernova

2) nearby black hole

3) an increase in the solar wind

4) nuclear fusion

what is a robin is it a herbivores or carnivores or omnivores or decompers

A string of holiday lights is connected to an outlet in a series circuit. When the lights are plugged in, the circuit is overloaded, causing a fuse to blow.

Let's say you place a metal tray of foam pieces on top of a Van de Graaff generator. You turn it on and nothing happens right away but in a few seconds the foam pieces begin flying out of the pan. Why does this happen? A.

g An astronaut stands on the surface of the Moon and drops a dictionary (with a mass of 8 kg) and a cell phone (with a mass of 200 g) at the same time from the same height. Which will hit the ground first? Ignore the effects of atmospheric friction.

A railway truck of mass 800 kg moving with a constant velocity of 5 m/s, collides and couples with another railway truck of mass 6+50 kg which is stationary.

A yo-yo can be thought of as a solid cylinder of mass m and radius r that has a light string wrapped around its circumference (see below). One end of the string is held fixed in space.

Why is time an independent variable and position is a dependent variable in a position versus time graph

A geologist estimates that a large boulder weighs 7840 N. What should he estimate the mass of this boulder to be? A. 650 kg B. 740 kg C. 780 kg D. 800 kg

Two objects have the same momentum. Do the velocities of these objects necessarily have (a) the same directions and (b) the same magnitudes? Give your reasoning in each case.

If you keep voltage constant and increase resistance resistance, what happens to current?