Free SACE Physics Flashcard Review
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How are launch-velocity components found for angleθ above horizontal?
uₓ=u cosθ and uᵧ=u sinθ, with signs set by the chosen axes.
What acceleration components describe an ideal projectile with upward positive?
aₓ=0 and aᵧ=−g; horizontal velocity stays constant while vertical velocity changes.
What happens to velocity and acceleration at a projectile’s apex?
Vertical velocity is zero; horizontal velocity may remain nonzero and acceleration remains downward.
When is flight time2u sinθ/g valid?
For negligible drag with launch and landing at the same height, not an arbitrary cliff launch.
How is flight time found for a landing below launch?
Solve the vertical displacement equation using the actual negative displacement and choose the physically relevant positive time.
Why do horizontal and vertical projectile equations use the same t?
They describe simultaneous components of one motion, so elapsed time links the independently accelerated directions.
How is impact speed reconstructed from components?
Use√(vₓ²+vᵧ²); add perpendicular components vectorially, not arithmetically.
What must accompany a speed to specify impact velocity?
A direction relative to a stated axis, or both signed components.
What is the maximum rise from launch for an ideal projectile launched with upward vertical component uᵧ?
uᵧ²/(2g), obtained by setting final vertical velocity to zero.
Why reject a negative-time landing root after a stated launch?
It belongs to the mathematical extension before t=0, outside the physical event being modelled.
Which direction does drag act during oblique motion through still air?
Opposite the velocity relative to air, generally with horizontal and vertical components.
What force balance defines vertical terminal speed?
Upward drag equals downward weight, giving zero net force and constant nonzero speed.
Can a falling object speed up while its acceleration decreases?
Yes. Downward acceleration can remain positive but shrink as drag approaches weight.
Why may equal-shape objects of different masses fall differently in air?
At the same speed, the same drag force produces different drag accelerations F/m, although ideal gravitational acceleration is the same.
What video evidence supports a claim of terminal speed?
Several successive interval velocities are constant within uncertainty, rather than one isolated speed reading.
How many time intervals separate six consecutive video positions?
Five; elapsed time is five divided by frame rate.
Why place a video calibration scale in the plane of motion?
A scale at another camera distance creates perspective error in the inferred displacement.
What does averaging repeated launches fail to remove?
A systematic offset such as measuring range from the wrong release point.
What should be measured as projectile range in a bouncing-ball experiment?
Horizontal distance to first impact, not the ball’s final resting location.
What makes an investigation evaluation useful?
Name a specific limitation, explain its likely effect and propose a feasible correction or discriminating measurement.