Projectiles - [Mechanics 2]. Flashcards
What is a projectile?
Any object thrown into space by the exertion of a force.
What is the first thing to do in a projectiles question if there isnt already one?
Draw a diagram of what’s happening and label on any relevant information.
What things do we mention are negligible for Projectiles?
- Dimensions of the object.
- Rotation/ Spin of the object.
- Air resistance on the object.
What equation involves Horizontal Velocity, Horizontal Displacement and Time?
Horizontal Velocity = Horizontal Displacement / Time.
What do we use for vertical acceleration in projectiles?
Gravity (9.8, 9.81 or 10ms-2).
We have to round our answer to appropriate sig fig - e.g.
* 9.8 to 2sf.
* 9.81 to 3sf.
* 10 to 1sf.
What things can act vertically on a projectile?
Weight (Vertical Acceleration) and Time.
If you have an angle of projection, what do you need to do?
Resolve the force into vertical and horizontal components.
How do you work out the velocity at any point?
Use Speed = Distance / Time if you can. Otherwise use SUVAT to solve.
How do you work out the Magnitude and Direction of the Velocity?
Form a triangle using Horizontal Velocity and Vertical Velocity and use Pythagoras’ theorem and using SOHCAHTOA to find the angle and Resultant Force.
What modelling assumptions can you make?
- No Air Resistance.
- The spin/ dimensions of the particle are not included.
What part of a vector is the horzontal component?
The ‘i’ part.
What part of a vector is the vertical component?
The ‘j’ part.
If something is moving Due North, what is its general vector form?
(0i + aj).
i = 0.
If something is moving Due East, what is its general vector form?
(ai + 0j).
j = 0.
If something is moving Due South, what is its general vector form?
(0i + aj).
i = 0.
