Mechanics M08-M16 Flashcards
What does the distance vs time graph look like? gradient, y-intercept = ?
Sloping increasing velocity.
gradient = velocity
y - intercept = starting distance.
What does the velocity vs time graph look like? gradient, area = ?
straight diagonal line
gradient = acceleration
area = distance
What does the acceleration vs time graph look like? y-intercept, area = ?
y - intercept = acceleration
area = velocity
How can we find the instantaneous velocity of an object from a distance-time graph?
Draw a tangent to the graph and calculate the gradient, which is the velocity at that point.
What is Newton’s 1st law?
An object will stay stationary or at a constant velocity unless acted on by a resultant force.
What is Newton’s 2nd law?
The force is equal to the mass x acceleration of the object.
What is freefall?
Freefall is when an object falls completely under its weight and drag forces are negligible.
How are the horizontal and vertical velocities of a projectile related?
Of a projectile going diagonally at force F, horizontal force = Fcos(theta) and vertical force = Fsin(theta). Horizontal forces are affected by friction, air resistance, etc. Vertical forces are affected by gravity and occasionally friction as well.
Projectile velocity horizontally doesn’t change as acceleration is 0, whereas horizontally there is acceleration so the velocity isn’t constant.
How is air resistance related to speed?
As an object’s speed increases the air resistances also increases, until the thrust is the same as the air resistance and the top speed is reached.
Why do objects reach a terminal speed?
The thrust/force is the same as the air resistance and the top speed is reached.
Draw a velocity-time graph for a parachutist.
Look at the google docs photo = https://docs.google.com/document/d/1aLsZsXrogX4M0yV2H6vs2SKbyk6WxlK8jMZ3rqVnwJs/edit
What are the 5 SUVAT equations?
- v = u + at
- s = ut + (1/2 x at^2)
- v^2 = u^2 + 2as
- s = (v+u)/2 x t
- s = vt - (1/2 x at^2)
After the 2.0s the man opens his parachute. Air resistance is greater than weight. Explain in terms of Newton’s laws of motion, why his velocity initially decreases?
Air resistance is greater than weight.
Hence resultant force is upwards, hence deceleration.
NEWTONS 1ST LAW INVOLVED.
After the 2.0s the man opens his parachute. Air resistance is greater than weight. Explain in terms of Newton’s laws of motion, why a terminal velocity is reached.
Once downwards force and upwards force of air resistance is equal, there is’y a resultant force and a terminal velocity is redached.
NEWTONS 3RD LAW
What is Newton’s 3rd Law?
Equal and opposite reaction forces, whenever two objects interact.
