Projectiles: a_x = 0 (constant horizontal velocity u cos θ); a_y = -9.8 m/s².
Connected particles: formulate F = ma equation for each mass, solve simultaneously.
💡 Worked Example Question
Exam-Style Question
Question:
Mass 4 kg on a 30° rough slope with μ = 0.2. Find acceleration down slope.
Model Solution & Mark Scheme:
R = mg cos 30° = 4(9.8)(√3/2) = 33.95 N.
Friction = 0.2 × 33.95 = 6.79 N.
Weight down slope = 4(9.8) sin 30° = 19.6 N.
ΣF = 19.6 - 6.79 = 12.81 N => a = 12.81 / 4 = 3.20 m/s².
❓ Practice Questions & Mark Schemes
Q1: Velocity v(t) = 3t² - 12t + 9. Find displacement from t=0 to 3.