Displacement, time and velocity
Velocity vs Speed
Speed is a scalar quantity measuring how fast an object moves (distance/time), while velocity is a vector quantity measuring speed with a specific direction (displacement/time).
What physical quantity tells you how fast and in what direction an object is moving?
Velocity
9.8 m/s2
You are given initial velocity, acceleration, and time. Which equation should you use to find final velocity?
v=v0+at
An object moves and returns to its starting point. What is its displacement?
Zero
Average velocity vs Instantaneous velocity
Average velocity is the total displacement divided by total time representing the overall rate of motion over a time interval.
Instantaneous velocity is the velocity at a precise, specific moment in time, calculated as the slope of the tangent line to a position-time graph.
At the highest point of a vertical throw, which quantities are zero and nonzero?
Velocity is zero; acceleration is nonzero.
A ball is dropped from rest. How fast is it moving after 2 s?
19.6 m/s downward
An object moves 10 m in the positive x axis and returns to its starting point. What was its displacement and distance?
0, 20 m
What does the slope of a position–time graph represent?
Velocity
A car is moving in the +x direction with constant negative acceleration. What is happening to its speed?
Decreasing
An elephant and a feather are dropped at a same height. Which one reaches the ground faster? Air resistance is negligible.
Both reach at the same time
An object moves so that its speed is constant and nonzero for 10 s. Is it possible for its average velocity to be zero? Explain.
Yes—if it reverses direction and returns to its starting position.
Why can average velocity be zero while average speed is not?
Because displacement can be zero while distance is not
Can an object have zero velocity but nonzero acceleration?
Yes; at the top of vertical motion
Q: A ball is thrown straight up at 12 m/s. How long does it take to reach max height?
1.22 s
An object’s displacement is zero over a time interval. What must be true about its velocity at some time during the interval?
The velocity must be zero at least once (or change sign).
If an object’s velocity is negative, must it be slowing down?
No
Draw the graphs of position vs time, velocity vs time, and acceleration vs time, considering acceleration is constant.
List all four kinematic equations........
sorry