Key relationship
x = x₀ + vₓt; y = y₀ + vᵧt; |v| = √(vₓ² + vᵧ²); a = 0.
Physics · Class 11
Independent x & y motion
Uniform motion in a plane has constant horizontal and vertical velocity components. Each coordinate evolves as a separate straight-line equation, but both use the same elapsed time. Combining the coordinates gives a straight path. Changing one component changes the path direction and speed.
Open the interactive experiment →One clock drives two coordinate equations.
தளத்தில் சீரான இயக்கத்திற்கு x மற்றும் y திசை வேகங்கள் மாறாமல் இருக்கும். இரு கூறுகளும் ஒரே காலத்தைப் பயன்படுத்துகின்றன. அவற்றை இணைத்தால் நேர்கோட்டுப் பாதை கிடைக்கும்.
Key notes, relationships and model limits
Remember
Uniform motion in a plane has constant horizontal and vertical velocity components. Each coordinate evolves as a separate straight-line equation, but both use the same elapsed time. Combining the coordinates gives a straight path. Changing one component changes the path direction and speed.
Common trap
The two component motions happen simultaneously, not one after the other.
Model limits
Inertial frame; constant x and y velocities; no forces change the motion. x/y traces share the same time. The path shown extends to t = 10 s. Distance equals displacement magnitude here because the path is straight without reversal.
What you will learn
Predict x/y coordinates; distinguish component velocity from speed; connect the path to the vector equation.
Try the experiment
Play the diagonal preset. Pause at a known time and calculate both coordinates. Make one velocity zero or negative.
Think of it this way
A boat moving east while a steady current carries it north has two simultaneous motions and one resulting path.
Worked example
With (x₀,y₀)=(1,−2) m and (vₓ,vᵧ)=(3,4) m/s, at t=2 s the position is (7,6) m; displacement is (6,8) m.
Why this matters
Separating components converts a two-dimensional vector problem into two simpler equations linked by time.
Before you start
Rectangular axes · Pythagoras · sine and cosine
Check your understanding
For vₓ=3 m/s and vᵧ=4 m/s, what is the speed?
- 7 m/s
- 5 m/s
- 1 m/s
Read the explanation
Speed is the velocity magnitude: √(3²+4²)=5 m/s. Components are perpendicular, so their magnitudes are not added directly.
Course connection: CBSE XI Motion in a Plane; NEET/JEE kinematics. Use the assumptions stated in each question.