Which of these is an indication that a chemical reaction has occurred?

1) melting of a substance

2) boiling of a substance

3) formation of a precipitate

4) freezing of a substance

What is the best explanation of work? A. Work occurs when a force acts on an object. B. Work occurs when force acts to hold an object in place. C. Work occurs when energy acts on an object. D.

A car travels 35.0 mph north for 1.00 hour, then 40.0 mph east for 0.0500 hour, and finally 50.0 mph northeast for 2.00 hours. Calculate the average speed.

How does the strong nuclear force hold the nucleus of an atom together? a) It overcomes the electrical force of attraction between protons in the nucleus. b) It overcomes the electrical force of repulsion between protons in the nucleus.

How is energy transferred between trophic levels in a food chain?

A force of 1.200*103 N pushes a man on a bicycle forward. Air resistance pushes against him with a force of 615 N. If he starts from rest and is on a level road, what speed? will he be going after 25.0 m?

Psychologists avoid studying emotions because they have little impact on behavior T F

Sheila lives in the seashore community of Beachview. At 6:00 a. m. one morning, she noticed that the local ocean water was at high tide. At approximately noon that same day, she noticed the water was at low tide.

How many pounds are in 427.06 g? 1 gram = 2.20 * 10-3 lb A. 194,118 lb B. 194.12 lb C. 939 lb D. 0.939 lb

Identify the possible source of earth's magnetic field

A nurse applies a horizontal force of 147 N on a bed that has a mass of 152 kg, The magnitude of the normal force acting on the bed is .967 N 5.00 N 1440 N 1490 N