P 3. Dynamics Flashcards
F = ma is in here
okay
Perhaps w=mg???
okay
Annnd there’s tension here as well.
T = mg + ma???
suppose there’s negatives
Wow there’s practically not much done in the booklet. It’s purely gonna be applied base for this one D:
Like i said, compare this to mechanics
But hey at least i can compare this to mechanics
It literally is mechanics
Tell me about the different types of forces, how it’s produced and what it does?
Weight = mg - caused by gravity
Magnetic = magnets - ?
Upthrust = ? - opposes motion
Air resistance/drag = ? - ?
Electrostatic = ? - ?
Friction = rough surface - always opposes motion
Thrust/driving force = ? - ?
Tension = is it? - really?
How to gain resultant net force?
- Check which one is dominating
- That minus the opposing forces
- Voila
Tell me the difference between mass and weight
Mass:
- Measure of matter in your body
- Measured in kg
- Is always the same
Weight:
- The force due to gravity
- Measured in newtons (N)
- Changes depends on the gravitational field of an object
Word equations:
Weight (N) = mass (kg) x acceleration (ms-2)
W = mg
Define Newton?
A resultant force of 1 newton is produced when a mass of 1kg accelerates at 1ms-2
What is Newton’s 1st law?
An object remains at state or at constant speed unless acted upon an external force
What is Newton’s 2nd law?
F = ma = m([v-u]/2) = (mv - mu)/t
- Acceleration of an object is directly proportional to the size of the resultant force acting
- Acceleration ^ = resultant force ^
- Therefore in graph = straight line
- Think deep about what u get from gradients too (mass)
Rate of change of momentum of an object is proportional to the resultant force acting on it, and takes place in the direction of the force
What is Newton’s 3rd law?
If you apply a push force on a wall, then the wall will push back with an equal and opposite force on you
Example:
Describe what happens to the two trolley cars when the spring is released?
- Trolley A exerts a force on trolley B
- Trolley B exerts an equal and opposite force on trolley B
- Both separating in opposite directions
What is linear momentum?
The product of its mass and its velocity
(p = mv)
Tell me about the principle of conservation of momentum?
Momentum is always conserved during a collision
In any collision within an isolated system, the total momentum of the interacting bodies remains constant
(M1 x U1) + (M2 x U2 = (M1 x V1) + (M2 x V2)
Equations/formulas needed to answer the questions?
Equations/formulas probably needed:
F - ma
W = mg
g = 9.81 ms-2
a = (v-u)/t
Honestly, the answers to most of these be self explanatory, except when it comes to ….
Tension:
A car of mass 1400kg is pulling a trailer of mass 600kg. It accelerates from rest to a speed of 9ms-1 in a time of 60s on a level road. Assuming all resistance forces are negligible:
a) Calculate total force on engine required to produce this acceleration
b) Calculate the tension force in the tow bar
a) Calculate total force on engine required to produce this acceleration
- a = (v-u)/t = (9 - 0)/60 = 0.15ms2
- 1400 + 600 = 2000kg (total mass)
- f = ma = 2000 x 0.15 = 300N
b) Calculate the tension force in the tow bar
Car (mass 1400):
E - t = 1400 x 0.15
300 - 1400 x 0.15 = T
= 90N
Caravan (mass 600):
T = 600 x 0.15
= 90N
E - T = m x a
E = the total force to go forward type shi
S’pose know this equation in general
