What pressing problem did the invention of the cotton gin solve?

A. removing seeds from cotton fiber

B. efficiently harvesting raw cotton

C. quickly plowing the cotton fields

D. irrigating the fields of cotton plants

the answer is A.

Who was the first person to observe the moon through a telescope

The full range of wavelengths of em waves is called the

The energy of light depends on the

While flying over the grand canyon the pilot

A stretched string is 2.11 m long and has a mass of 19.5 g. When the string is oscillated at 440 Hz, which is the frequency of the standard A pitch that orchestras tune to, transverse waves with a wavelength of 16.1 cm travel along the string.

A star has a mass of 1.36 x 1030 kg and is moving in a circular orbit about the center of its galaxy. the radius of the orbit is 2.1 x 104 light-years (1 light-year = 9.5 x 1015 m), and the angular speed of the star is 1.1 x 10-15 rad/s.

Floating in deep space, you find yourself at rest next to a small asteroid. You reach out and tap the asteroid with a hammer. What happens to you in this process?

You walk forward at 1.5 m/s for 8s. Your friend decides to walk faster and starts out at 2.0 m/s for the first 4 s. Then she slows down and walks forward at 1.0 m/s for the next 4s. Make a distance-time graph of your motion and your friend's motion.

If the coolant in a refrigerator was not compressed back into a liquid after it flowed through the refrigerator what would happen

A electric model train travels at 0.339 m/s around a circular track of radius 1.75 m. How many revolutions does it perform per second, i. e, what is the motion's frequency?