Physics- Topic 2/ Motion and Forces- Newton Flashcards
Newton’s first law
An object at rest will remain at rest and an object in motion will remain in at a constant velocity until acted on by an unbalanced force.
Newton’s second law
When forces are unbalanced/ a resultant force on an object or body doesn’t equal 0, the object will accelerate towards the direction of the resultant.
Newton’s third law
For every action there is an equal opposite reaction. An object A exerts a force on B, object B will exert an equal for on A.
When the resultant force is 0
The object moves at a constant speed or rest.
When the resultant force is not 0
The object will change direction or accelerate
Newton’s second law equation
Force(N) = Mass(Kg) x Acceleration (m/s^2)
F=MA
Weight equation
Weight(N)= Mass (Kg) x gravitational field strength (N/Kg)
W=MG
Resultant force
the difference between the forces, until only one or none equals different than zero
Weight
Weight is the force on an object due to the gravitational pull and their mass.
Difference between weight and mass.
Mass is the quantity of matter one can hold, and barely changes ( eating/ drinking) but weight changes due to the strength of gravity.
Why do things fall
Due to weight not gravity
Why do objects need different amount of force to move
Because a heavier object needs more force to be moved
Investigate the relationship between force, mass and acceleration by varying the masses added to a trolly
1) Raise the ramp so that the troll moves by itself at a constant velocity to reduce friction.
2) Measure the length of the card and fasten it onto the troll
3) Weight the combined mass of the trolly and the card
4)Place line gates near the two ends of the ramp attached to a data logger
5) Place a start point marker
6) Add weights to the pulley ( make sure the pulley is tightly secured) and attach this to the card via a string
7) repeat this
8) Repeat this with added weights
Reaction times
Touch = 0.15s
Sound= 0.17s
Sight = 0.25s
Drugs affect reaction time
Stimulant e.g caffeine = heighten alertness
depressant e.g alcohol= reduce alertness
Dangers of deceleration
Driver may lose control over the vehicle and the brakes my overheat.
Stopping distance
Thinking distance + Braking distance
Work done (J)
Force (N) x Distance (M)
How is the stopping distance affected
By drugs, friction, speed, mass, tyre and road quality.
Momentum
momentum is a quantity to describe an object with a mass in motion. Momentum (kg m/s)= mass (kg) xvelocity (m/s)
Newtons second law momentum
force (N) = change in momentum (kg m/s) /time taken (s)
How to measure human reaction times
The ruler dropping experiment
collision newton’s 3rd law
When two objects collide the total momentum before the collision is equal to the total momentum after the collision. They both exert an equal but opposite force.
