NEWTONS FIRST LAW OF MOTION Flashcards
(17 cards)
newton’s law of motion/law of inertia
an object will remain at rest or motion at constant velocity, unless acted upon by an external net (resultant) force
inertia
inertia is the resistance of an object to a change in its state of motion or rest
safety belts importance
- according to newton’s 1st law, an object will remain in motion at a constant velocity unless a net force acts upon it.
- when a car is in an accident and comes to a sudden stop, the person inside the car will continue to move in constant velocity.
- without safety belts, the person will make contact with the windscreen of the car, causing severe head trauma
- safety belts act as an applied force, preventing the forward motion of the person
newton’s second law of motion
if a net force acts on an object, the object will accelerate in the direction of the net force. the acceleration is directly proportional to the net force and inversely proportional to the mass of the object
acceleration
acceleration is the rate of change of velocity of an object
newton as the unit of force
one newton is the force that accelerates a mass of 1kg at 1m.s-² in the direction of the force. 1N=1kg.m.s.-²
relationship between acceleration and net force of an object
directly proportional therefore if the net force increases, acceleration increases, provided the mass remains constant and if the net force decreases, acceleration decreases provided the mass remains constant
relationship between acceleration and mass of an object
inversely proportional therefore if mass increases, acceleration decreases, provided the force remains constant and if mass decreases, acceleration increases, provided the force remains constant
what happens if object moves in a straight line but speed changes
- the object accelerates
- there is a net force
- the object is not in a state of equilibrium
- newton’s 2nd law is valid
what happens if objects speed and direction of motion both change
- the object accelerates
- there is a net force
- the object is not in a state of equilibrium
- newton’s 2nd law is valid
what happens if object moves at constant speed but changes direction
- the object accelerates
- there is a net force
- the object is not in a state of equilibrium
- newton’s 2nd law is valid
what happens if the object remains stationary
- there is no net force
- the object is in a state of equilibrium
- newton’s 1st law is valid
what happens if the object moves at constant velocity
- the object moves at constant speed in a straight line
- there is no net force
- the object is in a state of equilibrium
- newtons1st law is valid
newton’s third law of motion
if object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude
newton’s third law force pair
- forces are equal in magnitude
- act in the same line, but have opposite direction
- the same type of forces
- act on different objects
- never cancel each other out
effects of newton’s 2nd law on overloading
- according to newton’s 2nd law, the acceleration of an object is directly proportional to the net force and inversely proportional to the mass of the object
- if the vehicle is overloaded, the stopping distance will increase which can lead to serious accidents.
3 when brakes are applied, the force (friction) remains the same, but the increase in mass causes a decrease in negative acceleration, increasing the time and distance it takes for the vehicle to stop
newton’s third law during an accident
- according to newton’s third la, the force that two objects exert on each other is equal in magnitude but opposite in direction
- if two cars are in an accident, they will both exert the same amount of force on each other irrespective of their masses
