What is studying or working i only one field (this is for science 7th grade)

1. A rifle with a longer barrel can fire bullets with a larger velocity than a rifle with a shorter barrel.

Suppose a disk is 0.50 cm thick and 4.0 cm in diameter. If this disk supports half the weight of a 95 kg person, by what fraction of its thickness does the disk compress?

All the terrestrial planets have

The Bridge and the Rock Using energy considerations and assuming negligible air resistance, find the speed of a rock just before it hits the water if it is thrown from a bridge 16.4 m above water with an initial speed of 16.

When you lift a bowling ball with a force of 61.1 N, the ball accelerates upward with an acceleration a. If you lift with a force of 70.9 N, the ball's acceleration is 2.07a. Calculate the weight of the bowling ball.

Visualize five horizontal sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true? a.

The characteristics that follow are characteristics of two of Galileo's surviving double-convex lenses. The numbers given are magnitudes only; you must supply the correct signs. L 1: front radius 950 mm, rear radius 2700 mm, refractive index 1.

Which car has the most kinetic energy? A car of mass 1500 kg with speed 5 m/s or A car of mass 1300 kg with speed 3 m/s or a car of mass 1200 kg with speed 2 m/s or a car mass 1400 kg with speed 4 m/s

A 500 kg table with 4 legs rests on solid flat ground. I place 3 books on the center of the table with masses of 10 kg, 20 kg and 30 kg respectively. What is the normal force between the ground and one leg of the table?

Fluorine-21 has a half-life of approximately 5 seconds. What percentage of the original nuclei would remain after 20 seconds