If general relativity offers the best description of what happens in the presence of gravity, why do physicists still make use of Newton's equations in describing gravitational forces on Earth (when building a bridge, for example) ?

A railway truck of mass 800 kg moving with a constant velocity of 5 m/s, collides and couples with another railway truck of mass 6+50 kg which is stationary.

You have a box of pencils and each one has a cross-section of 0.002 m2. The maximum stress that each pencil can take is 22,500 pascals. How many pencils could be broken at once by a force of 135 newtons?

Suppose a monatomic ideal gas is contained within a vertical cylinder that is fitted with a movable piston. The piston is frictionless and has a negligible mass. The area of the piston is 3.02 10-2 m2, and the pressure outside the cylinder is 1.

Two forces are acting on a wheelbarrow. One force is pushing to the right and an equal force is pushing to the left. What can you say about the wheelbarrow's movement? A) It is slowing down. B) It is not accelerating.

Which of the following best describes work being done by someone's arms? a. a child building a sand castle b. a mother holding a baby c. a boy pushing on a tree d. a traveler carrying luggage

What is the approximate weight of a 20-kg cannonball on the moon if the acceleration due to gravity is 1.6m/s^2

A man consumes 2245 kcal of food in one day, converting most of it to maintain body temperature. If he loses half this energy by evaporating water (through breathing and sweating), how many kilograms of water evaporate?

If an eagle and a bumblebee are traveling at 8km/hr which has more momentum?

For each case, identify the force (including its direction) that causes the acceleration. (a) A sprinter at the very start of the race.

Select the effects of radiation below that are stochastic: associated with short-term, high-level exposure associated with long-term, low-level exposure include cancer and other DNA mutation include burns and radiation sickness