Projectile Motion
Table of Contents
Definition
- A projectile is a particle moving near the Earth’s surface under the influence of its weight only (directed downward).
- Horizontal velocity is constant.
- Vertical velocity just like free fall.
Horizontal Projection
Displacement Calculation
- For any constant acceleration: \(d = v_0t + \frac{1}{2}at^2\)
- For any special case of horizontal projection:
- Horizontal displacement: \(d_x = v_{0x}t\)
- Vertical displacement: \(d_y = \frac{1}{2}gt^2\)
Velocity Calculation
- For any constant acceleration: \(v_f = v_0 + at\)
- For any special case of horizontal projection:
- Horizontal displacement: \(v_x = v_{0x}\)
- Vertical displacement: \(v_y = gt\)
General Projection
Displacement Calculation
- The components of displacement at time \(t\) are:
- For projectiles:
- displacement components x and y for projectiles are:
Velocity Calculation
- The components of velocity at time \(t\) are:
- For projectiles:
- displacement components x and y for projectiles are:
Summary
Horizontal | Vertical | |
---|---|---|
Acceleration | \(a_x = 0\) | \(a_y = g\) |
Velocity | \(v_{ox} = v_0 cos\theta\) | \(v_{0y} = v_0sin\theta\) |
\(v_x = v_{0x}\) | \(v_y = v_{0y} + gt\) | |
Displacement | \(d_x = v_xt\) | \(d_y = v_{0y}t + \frac{1}{2}gt^2\) |
\(2gd_y = g_y^2 - (v_{0y})^2\) |
Uniform Circular Motion
- Uniform circular motion is motion along a circular path in which there is no change in speed, only a change in direction.
- Velocity tangent to path.
- Force toward center.
Centripetal Force
- It is the force that keeps the object in circular motion.
Centripetal Acceleration
\begin{equation*}
\begin{split}
a_c & = \frac{v^2}{R}; \\
F_c & = ma_c = \frac{mv^2}{R}
\end{split}
\end{equation*}
- where \(m\) is mass of the object, \(v\) is velocity, and \(R\) is radius of the circular path.
- acceleration directed toward the center of circular path.
Tangential Velocity
- when an object moves in a circular path at a distance \(r\) from the center, then the body's velocity is directed tangentially at any instant.
- the linear velocity is its tangential velocity at any instant.
Tangential Acceleration
- The rate of change of the tangential velocity of a particular in a circular orbit.
Formula (tho its not in the LAS): \(a_t = ar\)
- \(a_t\) is the tangential acceleration, \(r\) is the radius of the circular path, and \(a\) is the angular acceleration.
- always directs towards the tangent to the path of the body.