Hold a pencil in front of your eye at a position where its blunt end just blocks out the moon.
estimate the diameter of the moon, given that the earth-moon distance is 3.8 × 105 km. assume that the pencil has a diameter of about 0.7 cm, and it just blocks out the moon if it is held about 0.75 m from the eye.
express your answer using two significant figures.

The magnitude of the magnetic field at a certain distance from a long, straight conductor is represented by b. what is the magnitude of the magnetic field at twice the distance from the conductor? a. at twice the distance, the magnitude of the field is 4b.b. at twice the distance, the magnitude of the field is 2b.c. at twice the distance, the magnitude of the field is b/2.d. at twice the distance, the magnitude of the field is b/4.e. at twice the distance, the magnitude of the field remains equal to b.

Only 3% of the water on earth is usable by humans. even though that 3% is through the water cycle, we still need to be careful not to waste water.

What is the electric potential at a distance of 1.2 m from a 7.5 µc point charge? 5.6 × 104 v 8.1 × 104 v 5.6 × 1010 v 8.1 × 1010 v