Motion and forces (1-2) Flashcards
What is the difference between a vector and a scalar?
A vector has magnitude and direction whereas a scalar only has magnitude.
What are different vector and scalar quantities?
Scalar:
Speed, distance, mass, energy, temperature and time.
Vector:
Velocity, displacement, weight, momentum, force and acceleration.
How can you read a distance/time graph?
Gradient = steady speed Horizontal = no speed Curve = acceleration/deceleration
How can you read velocity/time graph?
Gradient = acceleration
Horizontal = steady speed
Area under graph = distance
What equation includes acceleration, change in velocity and time?
a = (v-u)/t
a = acceleration (m/s^)
v and u = final and initial velocity (m/s)
t = time (s)
What equation includes acceleration, final velocity, initial velocity and distance?
v^ - u^ =2ax
v and u = final and initial velocity (m/s)
a = acceleration (m/s^)
x = distance (m)
What are some typical speeds?
Walking - 1.4m/s Running - 3m/s Cycling - 5.5m/s Cars - 13 - 31m/s Aeroplane - 250 m/s Trains - 55 m/s Ferries - 15 m/s Sound - 340 m/s Wind - 5-20 m/s
What is acceleration in free fall?
10 m/s^
What happens when an object moves in circular orbit?
An object moving in a circular orbit at constant speed is constantly changing direction, therefore, it’s velocity is constantly changing so it is accelerating. There must be a resultant force which acts towards the middle of the circle (centripetal force).
What is inertial mass?
A measure of how difficult it is to change the velocity of an object. It is the result of force/acceleration (the ratio of force over acceleration).
What is newton’s third law?
When two objects interact, the forces they exert on each other are equal and opposite.
What is momentum?
The product of an object’s mass and velocity.
p = m x v
p = momentum (kg m/s) m = mass (kg) v = speed (m/s)
What equation includes force, change in momentum and time?
F = (mv - mu)/t
F = force (N)
m = mass (kg)
v and u = velocity (m/s)
t = time (s)
What is conservation of momentum.
In a closed system, total momentum before = total momentum after.
What is the stopping distance of a car dependant on?
The mass of the vehicle. The speed of the vehicle. Driver's reaction time. The state of the vehicle's brakes. The state of the road. The amount of friction between the tyre and the road.
