According to NASA, a rocket engine works by burning fuel and pushing the resulting hot gas out through an exhaust nozzle on the rear of the craft. Since every action has an equal and opposite reaction, as stated by Newton's third law, the force created by the escaping gases pushes the rocket forward, even in the vacuum of space.Know More
Rockets may use either liquid or solid fuel. There are many different types of rocket fuel, but they all have reactivity in common. When the fuel is mixed or ignited, it produces large volumes of gas, suitable for propelling the vehicle forward. Petroleum-based fuels were used in early rocketry experiments, but these fuels work best in an atmosphere. Cryogenic fuels, like liquid hydrogen and oxygen, were used in the Space Shuttle and had the advantage of being extremely efficient. However, the need to keep the fuels supercooled prevented their use in rockets that may need to stand for long periods of time.
Hypergolic fuels, like hydrazine, require no ignition source, reacting and producing thrust whenever the components of the fuel mixture come in contact with one another. The fuels used in the Apollo spacecraft were hypergolic to ensure there could be no ignition problems once the spacecraft reached the moon.Learn More
Isaac Newton's theory of gravity states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The law is represented as: F=G (m1m2)/R.Full Answer >
Scissors are composed of two different types of simple machines: wedge and lever. The scissors' blades are sharpened into wedges, and the arms that are squeezed together are levers.Full Answer >
A toilet paper dispenser is an example of a wheel and axle. The rod that supports the roll of toilet paper serves as the axle, and the toilet paper roll serves as the wheel. Like all wheel and axle machines, the toilet paper rotates concentrically around the cylindrical holder, which is fastened in place.Full Answer >
The formula for acceleration is given as a = (v2 - v1) / (t2 - t1), where "a" denotes the acceleration, "v2" indicates the final velocity, "v1" represents the initial velocity and "t2 - t1" is the time interval between the final and initial velocities. The SI unit for acceleration is meters per second squared (m/s2), while the British imperial unit is feet per second squared (ft/s2).Full Answer >