A coin flipped straight up is at the highest point of its flight. What is its velocity at that instant?
How long does a thrown object take to reach the top of its flight? You've already seen the two facts about the top: the velocity is zero for an instant, while the acceleration stays 9.8 m/s² downward.
Put v = 0 into the velocity equation v = v₀ + at, and solving for t gives the time of the rise.
Take up as positive: v₀ is the launch velocity, and a = −9.8 m/s². Make t the subject, the same rearrangement you've already used: t = (v − v₀)/a.
A ball is thrown straight up at 24.5 m/s. Air resistance is ignored. How long does it take to reach its highest point?
Write down the values in the question:
v = 0 (at the highest point)
v₀ = 24.5 m/s
a = −9.8 m/s² (taking up as positive)
Write down the equation:
v = v₀ + at
Make t the subject:
t = (v − v₀)/a
Substitute in the values:
t = (0 − 24.5)/(−9.8)
Simplify:
t = 2.5 s
Substituting v = 0 and a = −9.8 m/s² always gives t = (0 − v₀)/(−9.8). The two negative signs cancel, so the time comes out positive.
A ball is tossed straight up at 19.6 m/s. Air resistance is ignored. How long does it take to reach its highest point? Enter the time in seconds.
A tennis ball is hit straight up at 39.2 m/s. Air resistance is ignored. How long does it take to reach its highest point?
Write down the values in the question:
v = 0 (at the highest point)
v₀ = 39.2 m/s
a = −9.8 m/s² (taking up as positive)
Write down the equation:
v = v₀ + at
Make t the subject:
t = (v − v₀)/a
Substitute in the values:
t = (0 − 39.2)/(−9.8)
Simplify:
t = 4.0 s
A model ball launcher fires a ball straight up at 49 m/s. Air resistance is ignored. How long does the ball take to reach its highest point? Enter the time in seconds.
A dancer pushes off a trampoline, leaving it moving straight up at 14.7 m/s. Air resistance is ignored. How long after leaving the trampoline is the dancer at the highest point? Enter the time in seconds.
A soccer ball is kicked straight up at 34.3 m/s. Air resistance is ignored. How long does it take to reach its highest point? Enter the time in seconds.
A toy rocket's motor cuts out while the rocket is moving straight up at 58.8 m/s. From that moment it is in free fall, with air resistance ignored. How long after cutout does the rocket reach its highest point? Enter the time in seconds.
A ball leaves a volleyball player's hands moving straight up at 44.1 m/s. Air resistance is ignored. How long after launch is the ball momentarily at rest? Enter the time in seconds.