Answer:
- the age of the oldest stars
- patterns of background radiation
- how fast distant galaxies are moving away from us
Explanation:
According to the NASA, astronomers can estimate how old the universe is by comparing the age of the oldest stars and the rate of expansion of the universe. The rate of expansion of the universe is based on the Big Bang theory and it states that our universe is continuously expanding since it first developed. Astronomers measure Cosmic Microwave Background radiation resulting from the Big Bang.
The weight of an object is its mass times acceleration.
Weight of the box = (10kg)(9.81m/s^2) = 98.1N
If the box is at rest, then the normal force is equal to the weight of the box:
Normal force = 98.1N
If the box does not move, then the static friction force with 20 N is also 20N
Static Friction Force = 20N
If the box begins to move at 40, the maximum static friction force is equal to 40N
Maximum static friction force = 40N
Answer:
A)
Explanation:
Inside your CD player, there is a miniature laser beam called a semiconductor diode laser and a small photoelectric cell an electronic light detector. The laser flashes up onto the shiny side of the CD, bouncing off the pattern of pits and lands on the disc.
Answer:
72.936 Joule
Explanation:
Mechanical Energy = Potential Energy + Kinetic Energy
Kinetic Energy = (1/2) x m x V² = (1/2) x 1.8 x 4.8² = 20.736 J
Potential Energy = m x g x h = 1.8 x 10 x 2.9 = 52.2 J
Total Mechanical Energy = 20.736 + 52.2 = 72.936 Joule
