A projectile is launched at an angle above horizontal ground and travels through the air.
Assume that no upthrust acts on the projectile.
Which diagram shows the directions of the force or forces acting on the projectile at position X?
ANSWER: B
The Physics Behind answer
- Before reaching peak or point X,
- a velocity-dependent drag acts on the projectile, opposing the motion,
- this can be pictured as two drag components acting in the opposite directions of the vertical and horizontal velocities,
- downward gravity also acts on the projectile.
- When the projectile is at point X,
- the air resistance along the horizontal remains as the horizontal velocity is maintained along the horizontal [zero resultant force along horizontal so no change is velocity],
- the air resistance along the vertical is gone as it is velocity-dependent i.e. vertical velocity is zero at X, but the gravity is remains acting on the projectile's mass
- there are 2 forces and can be represented by vector arrows in option B.
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