Mechanics Flashcards
State the suvat equations
- s = (u + v)t / 2
- a = v - u / t
- s = ut + 1/2at2
- v2 = u2 + 2as
What is the difference between distance and displacement?
- Displacement is a vector
- Distance is scalar
What does a horizontal line represent on a displacement time graph?
- Stationary
What does a straight line where gradient is not zero mean on a displacement time graph?
- Constant speed
How is constant velocity forwards and backwards represented on displacement time graph?
- Constant velocity forwards is a straight line angled up
- Constant velocity backwards is a straight line angled down
How do you represent a stationary object on a velocity time graph?
- Horizontal line at zero
How do you represent a constant speed on a velocity time graph?
- Horizontal line
How do you represent a constant accleration on a velocity time graph?
- Straight line angled up
How do you represent a constant decelleration on a velocity time graph?
- Straight line angled down
What does gradient represent on a velocity time graph?
- Acceleration
How do you represent a stationary object on an acceleration time graph?
- Can’t be shown
How do you represent constant speed on an acceleration time graph?
- Horizontal line at zero
What represents a changing acceleration on an acceleration time graph?
- A straight line angled up or down
What does the gradient represent on an acceleration time graph?
- Jerk
Describe what a displacment, velocity and acceleration time graph would look like if a ball was thrown straight up into the air and then fell back down.
How do you find percentage error of multiple readings?
- Find range
- Range / 2 = Uncertainty
- %d = Uncertainty / Average value
How do you find percentage error of a single reading?
- Uncertainty = Resolution of instrument / Reading
- Then divide by 2
What is a vector quantity?
- Vector quantities have magnitude and direction
What is a scalar quantity?
- Has magnitude only
What is Newtons 1st law?
- States that a body will remain at rest or move with uniform velocity unless acted upon by a resultant external force
What Newtons 2nd law?
- States for a body of fixed mass, acceleration is directly proportional to the resultant force applied to the body
- F = ma
- Δp / t = F
What is Newtons 3rd law?
- States if object A exerts a force on object B then object B exerts an equal and opposite force on object A
What is the equation for gravitational field strength?
- g = F / m
What is the equation for weight?
- W = mg
What is the equation for momentum?
- p = mv
What is the conservation of momentum?
- Total momentum before = Total momentum after if no resultant external force acts
What is the moments equation?
- Moment = Fd
- Moment = Force * Perpendicular distance from pivot
What is the principle of moments?
- In equilibrium, total moments clockwise = total moments anticlockwise
What is the centre of gravity?
- The point at which all weight acts
What is the equation for impulse?
- Δp = Ft
What is the equation for kinetic energy?
- KE = 1/2mv2
What is the equation for GPE?
- GPE = mgh
What is the principle of concervation of energy?
- Energy cannot be created or destroyed only transfered from one form to another
What is the equation combining GPE and KE?
- 1/2mv2 = mgh
What are the equations for power?
- P = E/t
- P = W/t
- Energy transfered = Work done
- P = I2R
- P = V2/R
What are the equations for effeciency?
- Efficiency = Useful energy output / Total energy input
- Efficiency = Useful power output / Total power input
What should you do when dealing with projectiles?
- Treat horizontal and vertical motion separatly using suvat
What is the equation for work?
Work done = Force in direction of travel × Distance
What is a Newtons Third law pair of forces?
- Same type of force
- Same size
- Opposite direction
- Act of different bodies
- Same line of action
- Act for same time
Equation for velocity
- Velocity = displacement / time
If you get stuck think…
ENERGY, UNITS, RESULTANT FORCES, ACCELERATION
Core practical 1: acceleration of free falling object
- Independant variable
- Dependant
- Equation
- y=mx + c
- Graph to plot
- Equipment = Light gate and data logger
- Height dropped
- Final Velocity
- v2 = u2 + 2as
- y=mx + c
- y axis plot v2
- x axis plot s
What is the power equation that includes force?
- P=fv
What is change in momentum for one object?
- Change in momentum = final momentum - initial momentum
What must you remember whilst drawing a force free body diagram?
- CUT IT OUT OF THE PICTURE
- Only forces acting on the body
How do you calculate displacment for object traveling in curve or circle?
- Draw a straight line from start to finish and use pythag
