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Apologia Physics M4
Motion in Two Dimensions
Question | Answer |
---|---|
By adding displacements, | we can get overall displacement. |
We approach two-dimensional problems by | looking for the one-dimensional part of the problems. |
When a projectile is fired at an angle relative to the ground, | its motion is called parabolic. |
Parabolic means it | follows the curved path of a parabola. |
When we look at the components of a vector, | we really have the vector itself. |
Once a cannonball leaves the cannon, the only things acting on it is | gravity, |
Gravity only acts in the | y-dimension. |
Gravity does NOT affect the | x-component of velocity. |
The x-component of velocity | NEVER changes. |
The x-component of the velocity vector stays | exactly the same length and points in exactly the same direction for the entirety of the flight of the object. |
In the middle of a cannonball's trip, gravity has reduced the y-component of the ball's velocity to | zero. |
When the velocity is point in the same direction as gravity's pull, the y-component of the velocity | increases, making the object fall even faster. |
Parabolic motion is | motion that occurs when an object moves in two dimensions but has zero acceleration in one of those dimensions and a constant, non-zero acceleration in the other. |
When a projectile reaches its maximum height, the y-component is | zero. |
A projectile will land with the exact opposite velocity to what it | started with. |
The speed of a projectile is | the same when it lands as it was when it launched. |
The projectile reaches it maximum height at the | midpoint of its journey. |
The range equation from this module ONLY applies when | the target/end point is at the same level as the origin point of the projectile. |
We are also neglecting to take | air resistance into account throughout this discussion. |
We are calculating the range of a projectile when we | determine the distance that it travels in the x-dimension. |
initial speed = | Vo |
To determine the y-component of a projectile, we use | Voy=Vo*sin(O) O=angle |
If we know the initial velocity in the y-dimension, we can | calculate the time it takes for the projectile to reach its maximum height. |
g= | gravity |
range = | {original velocity squared * sin (2*angle)] / gravity (Equation 4.9) |
Equation 4.9 ONLY applies to | projectiles that land at the same height from which they are launched. |
In order to remove a function from one side of an algebraic equation, | take the inverse of the sign from both sides of the equation. |
Conventionally speaking, a positive sign means | upward motion. |
Conventionally speaking, a negative sign means | downward motion. |
When we are looking at a situation in which the end point is different in height from the starting point, we need to | find another way to solve the problem. |
When starting and ending height are different, we may have to solve for the | y-dimension and then use the information to solve for the x-dimension (or vice versa). |