Mechanics - Term 1 Flashcards
Suvat equations
V=u+at S=vt-1/2at^2 S=ut+1/2at^2 S=((u+v)t)/2 V^2=u^2+2as
NL1
The first law of inertia
An object at rest stays at rest and an object in motion stay in motion at the same velocity unless acted upon by a resultant force
NL2
The law of motion
The resultant force acting on an object is equal to the mass of the object multiplied by the acceleration of that object in that direction
F=ma (in specific direction)
NL3
For every action there is an equal and opposite reaction
Golden rules for suvat and nl2
Separate diagrams Label all forces State the direction that ur using nl2/suvat State the direction List suvat variables
When to use suvat to find nl2
When acceleration is constant we can use suvat to find the value of acceleration in a particular direction to deduce resultant force in that direction
When to use nl2 to find suvat
We can use resultant force in a particular direction to find acceleration and then use suvat to derive values for s u v a t
A block of mass 2kg is being pulled along a table by a string with tension T
The block is subject to a frictional force of 15N
The block is initially at rest and accelerates uniformally such that after 10s it has accelerated to 12m/s
Find T
T=17.4N
A car with mass 400kg is towing a caravan with mass 600kg
They are accelerating at 4m/s^2
What is the tension in the light, inelastic cable?
What is the driving force produced by the car?
T=2400N (remember it is the only force acting on the caravan)
d=4000N
A car of mass 800kg is pulling a caravan of 1400kg along a level road
They are connected with a light inextensible coupling
The resistance force acting on the car is 400N and is 700N on caravan
The driver accelerates so that the cars velocity goes from 12 to 15m/s over 27m
Calculate acceleration of car and caravan?
Calculate tension in the coupling?
Calculate driving force?
A=1.5m/s^2
T=2800
D=4400
