Projectile Range, Parallelogram of Forces

Vector and Trajectory Dynamics Lab (Physics - Std 11)

Vector and Trajectory Dynamics Lab

Physics - Std 11: Mechanics (Projectile Range, Vector Addition)

This lab focuses on the **kinematics of projectiles** and the **addition of forces (vectors)**. Use the interactive tools to calculate range, find resultant forces, and verify key vector theorems.

Mission Briefing: Key Equations & Formulas

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Projectile Range ($R$):

The horizontal range is given by (neglecting air resistance): $$ R = \frac{v_0^2 \sin(2\theta)}{g} $$

  • $v_0$: Initial Velocity ($\text{m/s}$)
  • $\theta$: Launch Angle (degrees)
  • $g$: Acceleration due to Gravity ($10 \text{ m/s}^2$)
Parallelogram Law (Resultant Force $R$):

For two vectors ($P$ and $Q$) inclined at angle $\alpha$:

$$ R = \sqrt{P^2 + Q^2 + 2PQ \cos\alpha} $$

Experiment 1: Projectile Range Optimization

Calculate the horizontal range ($R$) and verify the principle of complementary angles.

Initial Velocity ($v_0$)
20 m/s
Launch Angle ($\theta$)
30°
Calculated Range ($R$)
34.64 m
The range for $\theta = 60^\circ$ is also 34.64 m (Complementary Angle Principle).
Principle Verification

Experiment 2: Vector Resolution Challenge

Find the **Resultant Force ($R$)** given two forces ($P$ and $Q$) and the angle ($\alpha$) between them.

Force P (N)
10 N
Force Q (N)
15 N
Angle $\alpha$ (deg)
60°
Input your calculated resultant force and click 'Verify'.
Result Status
Complementary Angles in Projectiles:

The horizontal range ($R$) of a projectile is the **same** for two angles of projection, $\theta$ and $(90^\circ - \theta)$. These are called complementary angles. Maximum range occurs at $45^\circ$ where the complementary angle is itself $45^\circ$.

Vector Laws and Resultant Force

Parallelogram Law vs. Triangle Law:

The Parallelogram Law and the Triangle Law are two geometrical methods used to find the **resultant** (single vector that produces the same effect) of two or more vectors. The parallelogram method is typically used for forces originating from a single point.

Scalar vs. Vector:

A **scalar** quantity (e.g., mass, distance) is defined only by magnitude. A **vector** quantity (e.g., force, velocity) is defined by both **magnitude and direction**. Vector addition follows specific rules (like the Parallelogram Law), not simple arithmetic addition.

Equilibrant Force:

The equilibrant force is a single force that is **equal in magnitude** but **opposite in direction** to the resultant force ($R$). It is the force required to keep the system in equilibrium.

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