Grade 11 Projectile and Equilibrium Physics

📋 Course Outline

1. Velocity Vectors and Components
2. Relative Velocity and River Crossing
3. Horizontal Projectile Motion
4. Angled Projectile Motion
5. Moment of a Force
6. Equilibrium of Forces

📖 1. Velocity Vectors and Components

🔑 Key Concepts & Definitions

• Velocity vector: has both magnitude and direction

★ Must-know

📐 Formula — A velocity of magnitude $v$ at angle $\theta$ to the horizontal has components $v_x=v\cos\theta$ and $v_y=v\sin\theta$.

Further detail

• Two perpendicular velocity components of 20 m/s have a resultant magnitude of 28.3 m/s.

💡 Memory Hook

Picture perpendicular arrows forming a right triangle: horizontal, vertical, resultant.

📖 2. Relative Velocity and River Crossing

📝 Essential Points

📐 Formula — The velocity of B relative to A is $\vec v_{B/A}=\vec v_B-\vec v_A$.

• For a boat aimed perpendicular to a river bank, the crossing component determines time, while the current determines downstream drift.

📐 Formula — The resultant speed of perpendicular velocities $v_1$ and $v_2$ is $v=\sqrt{v_1^2+v_2^2}$.