A baseball leaves a table edge moving horizontally. Which statement describes its downward motion?
One ball is thrown sideways gently, at 2 m/s. A second is thrown hard, at 20 m/s. Does the hard throw change the fall? It does not. The reason is the one force acting on each ball.
Both balls are projectiles: once airborne, gravity is the only force acting on either one.
Gravity acts straight down. It has no horizontal part. A force changes velocity in its own direction. So gravity changes each ball's downward velocity, and nothing else about its motion.
The sideways speed does not enter. Whether a ball moves sideways at 2 m/s or 20 m/s, the force on it is the same gravity, acting the same way.
So both balls gain 9.8 m/s of downward speed each second. Their falls are identical.
Sana says a ball thrown sideways really fast gains downward speed more slowly than one thrown gently. Is she correct?
The feeling that a hard sideways throw softens the fall is common, and it is wrong. The sideways motion and the fall run in different directions, and the fall does not feel the sideways speed.
A hockey puck is knocked sideways off a railing. Why is its downward motion free fall?
Two identical rocks leave a cliff edge horizontally at the same moment, one at 5 m/s and one at 15 m/s. Compare the downward speed each gains in its first second.
Gravity is the only force on each rock, and it acts straight down.
The sideways speed does not enter.
Each rock gains 9.8 m/s of downward speed in its first second.
Both gain the same 9.8 m/s of downward speed.
One ball is tossed sideways at 3 m/s and another at 30 m/s, from the same ledge. Compare the downward speed each gains per second.
A squirrel knocks an acorn sideways off a roof gutter. Why does the acorn gain downward speed at the same rate as a dropped acorn?
A stone is thrown horizontally from a high bridge at 30 m/s and falls for 4.0 s. Enter the downward speed it gains, in m/s.
Which feature of gravity makes a projectile's fall identical at any sideways speed?