Consider projectile motion over level ground with negligible air resistance. The – [Free] B79
Consider projectile motion over level ground with negligible air resistance. The launch angle is greater than 0 degrees and less than 90 degrees. When is the velocity a minimum? 2 At the end of the motion. 3 4 5 1 At the beginning of the motion. q, At the highest point above the ground. q, At the midpoint of the motion. q,
![Consider projectile motion over level ground with negligible air resistance. The - [Free] B79](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20628%20254'%3E%3C/svg%3E)
Question
Consider projectile motion over level ground with negligible air resistance. The launch angle is greater than 0 degrees and less than 90 degrees.
When is the velocity a minimum?
- (a) At the beginning of the motion
- (b) At the end of the motion
- (c) At the midpoint of the motion
- (d) At the highest point above the ground
Answer
The correct answer is At the highest point above the ground.
Detailed Explanation
In projectile motion, the velocity of the object has two components:
- Horizontal component (Vx): This remains constant throughout the motion because there are no horizontal forces (neglecting air resistance).
- Vertical component (Vy): This changes continuously under the influence of gravity.
At the start, the projectile has both a vertical and horizontal velocity component. As it rises, gravity slows down the vertical component until it becomes zero exactly at the highest point.
Therefore:
- At the highest point, the vertical velocity component is zero.
- Only the horizontal component remains, which is less than the initial speed (since initially both components were combined).
- This means the magnitude of the velocity vector is smallest at this point.
Mathematically:
V = √(Vx2 + Vy2)
When Vy = 0, V equals only the horizontal component, making it the minimum value during the flight.
Final Conclusion
Thus, the velocity is minimized at the highest point above the ground.