5 Forces Flashcards
Scalar
Quantities which only have one magnitude (size).
E.g. volume, speed, mass, temperature
Vector
Quantities which have magnitude and direction.
E.g. displacement, velocity, acceleration, force
Displacement
Velocity
1) How far from a particular point.
2) How fast in a given direction.
Speed is a ______. The equation is ?. The units are ___ or ___.
1) scalar
2) distance / time
3) m/s or ms⁻¹
Forces are ______ quantities. It occurs when objects ________.
1) vector
2) interact
Give five examples of contact forces.
- Friction
- Air resistance/drag (plane)
- Tension (pulling an elastic band)
- Normal contact force (desk exerting force up onto a book to support its weight)
- Upthrust
Give three examples of non-contact forces.
- Gravitational force (satellite in orbit)
- Electrostatic force
- Magnetic force (magnets)
If an object is in ___________ its _________ _____ equals zero. If an object is in ___________ it _______ __________.
1) equilibrium
2) resultant force
3) equailibrium
4) doesn’t accelerate
Draw a free body diagram for a wheelbarrow being pushed by someone.
←•-→
→ = resultant force
acceleration equation with units
a = v-u / t m/s² = m/s ÷ s
What do the following symbols mean? • s • u • v • a • t
1) s = displacement (m)
2) u = inital/starting velocity/speed (m/s)
3) v = final velocity/speed (m/s)
4) a = acceleration (m/s²)
5) t = time (s)
force equation with units (Newtons’s 2nd law)
F = ma N = kg * m/s²
An object traveling in a circle can have a constant speed, but its ________ __ _____ ________.
_______ is the tendency for objects to continue in the same state of ______.
1) velocity is still changing
2) Inertia
3) motion
If an object falls in a _____, it eventually reaches a _______ ________ which we call its ________ ________.
1) fluid
2) maximum velocity
3) terminal velocity
1) Centripetal force direction
2) What provides centripetal force?
3) What affects the centripetal force?
1) Force always points towards the centre of the circle
2) Friction provides the centripetal force
3) Velocity and the radius of the circle affect the size and the centripetal force acting on the car
Name some factors which affect braking distance.
- Road conditions: adverse weather conditions e.g. wet/icy/snowy roads
- Vehicle conditions: worn brakes, worn tyres, over-inflated tyres, under-inflated tyres
- Weather conditions
Newton’s 3rd Law
- 𝗙𝗼𝗿 𝗲𝘃𝗲𝗿𝘆 𝗮𝗰𝘁𝗶𝗼𝗻, 𝘁𝗵𝗲𝗿𝗲 𝗶𝘀 𝗮𝗻 𝗲𝗾𝘂𝗮𝗹 𝗮𝗻𝗱 𝗼𝗽𝗽𝗼𝘀𝗶𝘁𝗲 𝗿𝗲𝗮𝗰𝘁𝗶𝗼𝗻.
- When one object exerts a force on another, the other object exerts a force back
- The reaction force is of the same type and is equal in size but opposite in direction
equation for stopping distance
stopping distance = thinking distance + braking distance
Hooke’s law (equation)
force = spring constant * extension(compression) F = ke N = N/m * m
What do the following symbols mean:
• k
• e
1) k = spring constant
2) e = extension
equation for elastic potential energy
E = 0.5 * spring constant * (extension)² E(x) = 0.5 * k * e² J = 0.5 * N/m * m²
1) Equation for momentum with units
2) Equation for total momentum
momentum = mass * velocity
kg m/s = kg * m/s
total momentum = 1st momentum + 2nd momentum
equation for rate of change in momentum
F = m * Δv / Δt N = kg*m/s / s
equation of motion
v² = u² + 2as m/s = m/s + (2 * m/s² * m)
equation for kinetic energy
E(k) = 0.5 * m * v² J = 0.5 * kg * m/s²
equation for weight
weight = mass * gravitational field strength W = mg N = kg * N/kg
equation for pressure in a column of liquid
P = height of column * density of liquid * gravitational field strength P = hρg Pa = m * kg/m³ * N/kg
If a see-saw is balanced, what happens in terms of moments?
When balanced the clockwise moment is equal to the anticlockwise moment.
⚖️ ↻moment = ↺moment
If one person sits on the left side of a balanced see-saw what happens in terms of moments?
The see-saw turns anticlockwise because now the clockwise moment is smaller than the anticlockwise moment.
↻moment < ↺moment
What can you look at on a displacement-time graph to find where something is moving the slowest?
- You look at the gradient
* Lowest gradient is the slowest
Why does pressure increase with depth?
- Greater depth, greater the weight above that point
* Greater the force on a surface at this point
equation for pressure
P = force normal to a surface / area of that surface P = F / A Pa = N / m²
Equation for moment of a force (turning effect)
M = force * distance Nm = N * m M = Fd
Equation for work done
work done = force * distance (moved along line of action of force)
J = N * m
W = Fs
