Astrophysics missions vie for NASA money

Rockets range in size from small fireworks that ordinary people use to the enormous Saturn V that once propelled massive payloads toward the Moon. The propulsion of all rockets, jet engines, deflating balloons, and even squids and octopuses are explained by the same physical principle: Newton's third law of motion. The matter is forcefully ejected from a system, producing an equal and opposite reaction on what remains.
The motion of a rocket in space changes its velocity (and hence its...

A rocket's velocity in the presence of a gravitational field is decreased by the amount of force exerted by Earth's gravitational field, which opposes the motion of the rocket. If we consider thrust, that is, the force exerted on a rocket by the exhaust gases, then a rocket's thrust is greater in outer space than in the atmosphere or on a launch pad. In fact, gases are easier to expel in a vacuum.
A rocket's acceleration depends on three major factors, consistent with the equation for the...

According to Newton's law of gravitation, the gravitational force on a body is proportional to its mass. According to Newton's second law of motion, the acceleration produced by an external force is inversely proportional to the force. Hence, the acceleration of an object under an external force of gravitation is independent of its mass.
The acceleration of an object close to the Earth, because of the Earth's gravitational pull, is called the acceleration due to gravity. It is always directed...

The gravitational acceleration of an object near the Earth's surface is called the acceleration due to gravity. It can be measured by conducting simple experiments on Earth. However, such an experiment is impossible to conduct on the surface of other planets.
Astronomical observations are thus used to measure the acceleration due to gravity on other planets. This can be determined by observing the effect of a planet's gravity on objects close to it. The crucial factor that helps in this...

In an experiment conducted during a Mars mission, a rover propels a projectile with an initial velocity, and the projectile rebounds after colliding with the Martian surface. To ascertain the maximum height attained by the projectile after this collision, the known restitution coefficient and acceleration due to gravity are employed.
By designating the launch point as the origin and utilizing kinematic equations, the vertical component of the projectile's velocity at the point of impact is...

Newton's second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes in motion. Newton's second law is quantitative and is used extensively to calculate what happens in situations involving a force. All external forces acting on a system add together to produce a net force Fnet. A larger net external force produces a larger acceleration. This acceleration is directly proportional to, and in the same direction as,...