Related Formula
vₓ² - uₓ² = 2 aₓ x$$v_x^2 - u_x^2 = 2 a_x x$$
vy = uy + ay t$$v_y = u_y + a_y t$$
Core Logic
Analyze the motion along the x-axis first to find the final x-velocity component (uₓ = 5 m/s$u_x = 5\text{ m/s}$, aₓ = 3 m/s²$a_x = 3\text{ m/s}^2$, x = 84 m$x = 84\text{ m}$):
vₓ² - 5² = 2(3)(84)$$v_x^2 - 5^2 = 2(3)(84)$$
vₓ² - 25 = 504 vₓ² = 529 vₓ = 23 m/s$$v_x^2 - 25 = 504 \implies v_x^2 = 529 \implies v_x = 23\text{ m/s}$$
Step 1: Compute time interval
Using the velocity relation along the x-axis:
vₓ = uₓ + aₓ t 23 = 5 + 3t 3t = 18 t = 6 s$$v_x = u_x + a_x t \implies 23 = 5 + 3t \implies 3t = 18 \implies t = 6\text{ s}$$
Step 2: Evaluate y-axis velocity component
Since uy = 0$u_y = 0$ and ay = 2 m/s²$a_y = 2\text{ m/s}^2$, calculate vy$v_y$ at t = 6 s$t = 6\text{ s}$:
vy = 0 + 2(6) = 12 m/s$$v_y = 0 + 2(6) = 12\text{ m/s}$$
Step 3: Total net speed calculation
v² = vₓ² + vy² = 23² + 12² = 529 + 144 = 673$$v^2 = v_x^2 + v_y^2 = 23^2 + 12^2 = 529 + 144 = 673$$
v = √(673) m/s$$v = \sqrt{673}\text{ m/s}$$
Comparing this with √(a)$\sqrt{a}$ yields a = 673$a = 673$.
Pattern Recognition
Splitting coordinates explicitly isolates vector calculation lines cleanly, optimizing equation selections relative to independent components.
Chapter Mix
Class 11 Physics: Kinematics