Newton's laws Flashcards
what is newton’s first law?
the law of motion
what did newton’s first law inscribe?
an object remains in the same state of motion unless a resultant force acts on it
what does it mean when the resultant force of an object is zero? (2)
- the stationary object stays stationary
- the moving object continues to move at the same velocity (at the same speed and in the same direction)
what is uniform motion?
constant velocity
what is terminal velocity?
maximum speed of an object
what can you deduce of the resultant force if the resultant forces acting on an object are balanced?
the resultant force is zero
what can you deduce of the resultant force if the resultant forces acting on an object are not balanced?
the resultant force is NOT zero
what happens when non-uniform motion occurs? and what does it affect?
-speed or direction changes, which affects velocity
will opposite forces affect each other? (different axis)
- no
- horizontal forces will not affect the vertical movement and the vertical forces will not affect the horizontal movement.
- describe the correlation between the vertical/ horizontal forces ?
- what effect does this have on the resultant force?
- what assumption can you make about acceleration?
- if the vertical/ horizontal forces are equal in size and opposite in direction, they are balanced,
- the vertical/ horizontal resultant force is zero.
- this means that there is no vertical/ horizontal acceleration.
what is newton’s second law (equation)?
F = ma Force(N) = mass(kg) x acceleration(m/s^2)
The (F=ma) equation shows that the ACCELERATION of an object is:
- proportional to the resultant force on the object
- inversely proportional to the mass of the object
what is the correlation between acceleration and force & mass?
- acceleration increases if the resultant force on it increases
- acceleration decreases if the mass of the object increases.
what is the ratio of force over acceleration called?
-inertial mass.
what is inertial mass?
-a measure of how difficult it is to change the velocity of an object.
what is the motto for newton’s third law?
every action has an equal and opposite reaction
what happens when two objects interact according to newton’s third law?
whenever two objects interact, they exert equal and opposite forces on each other
it is important to remember that the two forces:
act on two different objects
are of the same type (e.g contact forces)
3 examples of contact forces:
- a cat sat on the ground
- pushing a pram
- car tyre on a road
A cat sits on the ground
- the cat pulls the Earth up
- the Earth pulls the cat down
Pushing a pram
- the person pushes the pram forwards
- the pram pushes the person backwards
Car tyre on a road
- the tyre pushes the road backwards
- the road pushes the tyre forwards
example of a non contact force:
A satellite in the Earth’s orbit
- the Earth pulls the satellite
- the satellite pulls Earth
what does newton’s third law state?
-if body A exerts a force on body B, then body B will exert an equal opposite force on body A
what is the weight of an object (directly) proportional to?
what assumption can you make about this regarding a given gravitational field strength?
- weight of an object is directly proportional to its mass
- the greater the mass of the object - the greater its weight is.
weight equation: (include units)
weight (N) = mass(kg) × gravitational field strength (N/kg)
w=mg
how do we make a measurement of weight?
how can we do this?
what predictions can you make with evidence correlating to one of newton’s laws?
- we have to measure the force pulling the object towards the centre of the Earth.
- we do this by balancing it with a known force.
- if the object is stationary, Newton’s third law then tells us that the known force is the same as the weight.
how does a spring balance work?
what does the distance stretched correlate to?
- it will stretch until the force from the spring is enough to balance the weight of the object,
- the distance the spring in it has stretched indicates the force it is exerting to hold up the object.
what did newton’s second law state?
if a non-zero resultant force acts on an object, it will cause it accelerate
what is inertia?
the tendency for the motion of an object to be remain unchanged
