The light gathering power of a reflecting telescope is directly related to the area of the primary mirror: Area = pi x d^2 / 4
(Where d is the diameter of the mirror)
Set up a fraction to compare the light gathering power of a 10- meter diameter (Keck) telescope with that of a human pupil. The human pupil has a diameter of about 5 millimeters. How many times more intense is the light gathered by a Keck telescope, than light gathered by the human eye.

Atruck driver is attempting to deliver some furniture. first, he travels 8 km east, and then he turns around and travels 3 km west. finally, he turns again and travels 13 km to his destination. what is the drivers distance

Two horses begin at rest. after a few seconds, horse a is traveling with a velocity of 10 m/s west, while horse b is traveling with a velocity of 13 m/s west. which horse had a greater acceleration? a. horse a because its change in velocity was greater than horse b's in the same time. b. horse b because its change in velocity was greater than horse a's in the same time. c. horse b because its change in velocity was the same as horse a's, but it took less time. d. both horses had the same acceleration.

Which of the following examples illustrates static friction? a box sits stationary on a ramp. a ball rolling on the lawn eventually comes to rest. a car rounds a curve on a road. a fish swims upstream.