AP Physics C: Mechanics / Unit 1: Kinematics
1.5 Motion in Two or Three Dimensions
Notes
Split vectors into components: $v_x=v\cos\theta$, $v_y=v\sin\theta$.
- Projectiles: horizontal velocity is constant; vertical motion has $a=-g$.
- Horizontal and vertical motions are independent.
Practice
A ball is launched at 10 m/s at 30°. Its horizontal velocity:
$10\cos30°$.
A ball rolls off a table at the same moment another is dropped from the same height. Which lands first?
Same vertical motion.
At the top of a projectile's path, the velocity is:
$v_y=0$, $v_x$ stays.
$\vec r(t)=2t\,\hat i+t^2\,\hat j$. $\vec a(t)=$
Differentiate twice.
Ready for more? Take the Unit 1 test.