falling safely Flashcards
what was galileo’s theory?
that objects drop at the same rate despite their mass
what is the force acting on a parachute called?
air resistance or drag
what does the size of the air resistance force on a falling object depend on?
its cross-sectional area - the larger the area the greater the resistance
its speed - the faster it falls the greater the air resistance
what is terminal speed?
where the forces acting on a person are balanced
explain what is happening to a parachutist who has 600 N of downward force acting on him?
the parachutist accelerates, displacing more air molecules every second. The air resistance force increases. This reduces his acceleration. So the higher the speed the more air resistance
explain what is happening to a parachutist who has a balanced force acting on him?
the parachutists weight is equal to the air resistance. The forces are balanced. He is travelling at a terminal speed
explain what is happening to a parachutist who has opened his parachute?
when the parachute opens the upward force increases as there is a much larger surface area, displacing more air molecules every second. So the larger the are the more air resistance. Therefore he decelerates displacing fewer air molecules each second, so the air resistance force decreases
explain what happens to a parachutist after the parachute has been deployed?
the parachutist reaches a new slower terminal speed when his weight is equal to the air resistance once more, so he lands safely
what is the force acting on each kilogram of mass due to gravity?
g=10 N/kg on earth
give 3 characteristics of the gravitational field strength? i.e. what causes it to vary
it is unaffected by atmospheric conditions
it varies with position on the earth surface
it varies with height above or depth below the earth’s surface
