What do astronomers use to calculate the age of the universe

In space, a stationary light source emits green light at a frequency of 5.50*10^14Hz. A spaceship approaches the light at a speed 1.50*10^7m/s. What is the frequency of the light that is perceived aboard the spaceship. (the speed of light is 3.

The process in which bone cells gradually replace cartilage is called?

Why does th ground and atmosphere get warm during the day

Red light from three separate sources passes through a diffraction grating with 6.60*105 slits/m. The wavelengths of the three lines are 6.56 * 10-7m (hydrogen), 6.50 * 10-7m (neon), and 6.97 * 10-7m (argon).

A 20 kg mass is dropped from a tall rooftop and accelerates at 9.8 m/s2. What is the weight of the dropped object?

Michael wanted to measure the temperature of an object. Which SI unit should he use? a. milliliter b. kilogram c. Fahrenheit d. Kelvin

Who descover gravity and when?

What is the magnitude of the angular acceleration of the salad spinner as it slows down?

What is the current in a 10v circuit if the resistance is 20Ohm?

A motorist is traveling at 20 m/s. He is 60 m from a stoplight when he sees it turn yellow. Is reaction time, before stepping on the brake, is 0.50 s. What steady acceleration (slowing down) while braking will bring him to a stop right at the light?