A basketball is at the highest point of its flight. What is the magnitude of its acceleration at that instant? Enter the value in m/s².
You've already seen that a ball at the top of its flight has zero velocity. Yet its acceleration is still 9.8 m/s² downward. Zero velocity looks like nothing happening. How can the acceleration be anything but zero?
The answer comes from keeping two different questions apart: the velocity says how fast the position is changing; the acceleration says how fast the velocity is changing.
At the top the velocity is zero but it isn't staying zero — upward an instant before, downward an instant after. A zero that's mid-change is exactly what a nonzero acceleration looks like.
A tossed coin is momentarily at rest at the top of its flight. Why is its acceleration still 9.8 m/s² downward at that moment?
Acceleration says how the velocity is changing, and the coin's velocity is changing at that instant: upward just before, downward just after.
A changing velocity means a nonzero acceleration, even while the velocity itself passes through zero.
The acceleration stays 9.8 m/s² downward, because gravity keeps pulling downward at every instant of the flight, including the moment the object is momentarily at rest at the top.
A ball tossed straight up is momentarily at rest at the top of its flight. Which statement correctly describes its acceleration there?
A student says: 'At the very top the ball stops, so for that instant its acceleration is zero.' What is wrong with the claim?
At the top of its flight a tossed ball's velocity is zero. Which observation shows that its velocity is changing at that very instant?
A beanbag tossed straight up is momentarily at rest at the top of its flight. Which statement describes what gravity is doing at that moment?
Two students watch a ball reach the top of its flight. Amir says its acceleration there is zero because the ball is momentarily at rest. Bea says its acceleration there is 9.8 m/s² downward. Who is right, and why?
A juggling pin thrown straight up is at rest for an instant at the top of its flight. An instant later it is moving downward. Which quantity had to be nonzero at the top to make that happen?