If 50% of a radioactive element remains after 4000years what is the half life

Gravitational force varies (changes) inversely with what?

Planets move around the sun in elliptical orbits. True. False

As Aubrey watches this merry-go-round for a total of 2 minutes, she notices the black horse pass by 15 times. What is the period of the black horse?

The Flic-Flac is a spider that flips explain why?

A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heat from a hightemperature reservoir. What is the efficiency of this engine?

What property of sound enables us to distinguish one sound source from another?

The table below shows the right ascensions of two stars at a location. Star 1 - 4 right ascension (in Hour) Star 2 - 3 right ascension (in Hour) Which of these statements is correct about the stars?

H-2 + H-3 → He-4 + Consider the nuclear reaction that takes place in the sun. Two nuclides of hydrogen fuse to form helium. Is helium the only product of this reaction? If no, identify any additional products. A) Yes, He-4 is the only product. B) No.

Hat is a scientific theory? Make up your own scientific theory.

Which of the following is an example of a velocity? O A. 12 m/s O B. 45 km/hr south O C. 55 km/hr D. - 5 m/s2 east