P9&10- Force and Motion Flashcards
How do you calculate resultant force?
Resultant Force (N)= Mass(kg) x Acceleration(m/s)
What are Scalar Quantities?
Only have magnitude or size (kg, m).
What are Vector Quantities?
They have both magnitude and direction (km east).
What is resultant force?
A single force that has the same effect as two or more forces.
What does Newtons Second Law say about Acceleration?
Directly proportional to the resultant force of the object.
Inversly proportional to the mass of the object.
What is Inertia?
The tendancy of an object to stay at rest or to continue it’s uniform motion. (Stop or continue going)
What is the weight of an object?
The force acting on a object due to gravity measured in newtons.
What is the mass of the object?
The quantity of matter in the object, measured in Kg.
If the mass of a object is 1kg then what is the weight of it?
9.8 N (gravity)
If the mass of an object is 5kg what is its weight?
50 N (5x10)
What is the Equation of Weight?
Weight (N) = mass (kg) x gravitational field strength (N/kg)
What is Terminal Velocity?
It’s the velocity a object finally reaches when falling, the weight of the of the object is equal to the frictional force on the object.
What is the resultant force of an object when its at terminal velocity?
0 , as the force (friction and weight) are equal.
What factors affect the braking force needed to stop?
The speed of the vehicle and mass of it.
How do you find stopping distance?
Stopping distance = Thinking distance + Braking distance
What is the thinking distance?
The distance travelled by the vehicle during in the time it takes the driver to react.
What is the Breaking Distance?
The distance travelled by the vehicle during the time the braking force acts.
Equation for thinking distance?
Distance= speed x reaction time
4 factors affecting stopping distance are?
A
What equation for breaking force?
B Force = Mass x Acceleration (same as resultant force)
How do you calculate deacceleration?
A (deacceleration) = -U^2 (initial speed) / 2 x S (distance travelled)
When is a object called elastic?
If it returns to is original shape after removing the force deforming it.
What is extension?
The difference between the length of the object and its original length.
What does it mean when a spring is beyond the limit of proportionality?
The extension of the spring is no longer proportional to the force applied to the spring.
What does Hooke’s Law state?
The extension of a spring is directly proportional to the force applied, as long as its limit of proportionality is not exceeded.
What is the equation for the extension of the spring?
Length at extension - original length
What is Hooke’s Law Equation (spring constant)?
Force Applied = Spring Constant x Extension
What is the Equation for Momentum?
Momentum (kg m/s) = mass (kg) x velocity (m/s)
How do you find Inertial mass?
Force / Acceleration
What is the general law of the Conservation of Momentum?
In a closed system, the total momentum before an event is equal to the total momentum after the event.
What the centre of Mass?
The point of mass in which it is concentrated.
