Chapter 4- Newtons Laws Flashcards
What is a Force?
Any push or pull
What do forces do to an object?
Forces may change the motion of an object. They may combine with other forces to affect
motion.
Contrast Contact and Field Forces
Contact forces act between objects that are in contact with each other. The forces only act
when the objects are in contact. Ex: Friction, ordinary pushes and pulls.
Field forces act without contact. Ex: Gravity, Electromagnetism.
What is Inertia?
Inertia is the tendency of an object to resist a
change in its motion.
What is Mass?
Mass is a measure of the quantity of matter in an object, and of the Inertia of an object.
Why is Mass important for force and acceleration?
mass resists acceleration
What is Equilibrium?
The state at which the net forces acting on an object equal 0
How to objects move when in equilibrium?
They move at a constant velocity, or don’t move at all
How do objects move when there is a net force acting on them?
Objects accelerate in the direction of net force, in direct proportion to net force, and in inverse proportion
to mass.
State Newton’s second law according to force, mass, and acceleration?
Acceleration is directly proportional to net force and inversely proportional to mass
What is Friction?
Friction is a force that acts between surfaces in contact that resists motion between the objects.
Contrast Kinetic and Static Friction
Static friction acts between surfaces that are not moving with respect to each other. It builds in response to applied
force and acts to resist the start of motion, up to a maximum amount.
Kinetic friction is a constant force that acts to resist the motion of objects in contact with each other that are
moving with respect to each other.
What is weight?
Weight is the force of gravity acting on an object from the planet that it is on.
How do we calculate weight
Fg=mg
Gravitational force = mass times gravity
What do you multiply kg to get lbs
2.2
Compare the weight of an object on the moon and earth
An object weighs less on the moon than on Earth because the moon has weaker gravity, due to its much smaller mass than Earth.
Explain in terms of gravitational force and Newton’s 2nd Law why two objects of differing mass still experience the same acceleration due to gravity?
Fg=mg a=Fnet/m In free fall Fnet=Fg A=mg/m A=g
What is Newtons law of universal gravitation?
All objects attract all other objects through gravity. That attraction is proportional to the masses of the objects, and inversely proportional to the square of the distance between them.
What is momentum?
Momentum is: Mass in motion, Inertia in motion, but best described as a measure of how hard it is to stop a moving object. Momentum = mass x velocity.
What is impulse?
Impulse is Force applied for some amount of time. Impulse = net force x time.
How are impulse and momentum related?
Impulse equals change in momentum.
What is the law of Conservation of Momentum?
The momentum of any closed system does not change.
What is a closed system?
A closed system has no external forces acting on it that may change the momentum of the system, and there are no changes in mass within the system.
How do airbags save lives?
Airbags reduce the force acting to change the momentum of your body by increasing the amount of time over which your momentum is changed.
