Motion Words
What word means the straight-line change from an object's starting point to its ending point, including direction?
Displacement
Which quantity tells how fast something moves AND the direction it moves?
Velocity
On a distance-versus-time graph, which variable belongs on the vertical (Y) axis?
Distance.
What is the is the unit used to measure force?
Newtons
A soccer ball stays still until kicked. Which of Newton's laws explains this?
First Law (inertia).
A scooter travels 36 m east, then 12 m west. Find its total distance AND displacement.
Distance = 48 m. Displacement = 24 m east.
A bike travels 45 m in 9 s. What is its average speed?
45 ÷ 9 = 5 m/s
A flat segment on a distance-time graph lasts from 4 s to 9 s. How long was the object stopped?
5 seconds
A cart is pushed with 9 N left and 13 N right. What is its net force?
4 N to the right.
A 6 kg cart accelerates at 2 m/s². Find net force AND name the law.
ANSWER: 12 N, Newton's Second Law (F = ma).
Two students are sitting together on a moving bus. Explain how they can be at rest relative to each other but moving relative to the sidewalk.
Their positions don't change relative to each other, but both change position relative to the sidewalk.
A car changes direction while keeping a steady speed. Is it accelerating?
Yes. Changing direction changes velocity, so it is accelerating.
On one distance-time graph, Line A rises 12 m in 3 s. Line B rises 8 m in 4 s. Which object is faster?
A: 4 m/s. B: 2 m/s. Line A is faster.
A box moves right at constant velocity. What is its net force? Explain.
0 N. Its velocity does not change, so forces are balanced.
A swimmer pushes water backward and moves forward. Name the law and identify the two interacting objects.
ANSWER: Third Law. Swimmer pushes water backward; water pushes swimmer forward.
A dog walks 9 m north, 4 m south, then 3 m north. Calculate distance and displacement.
Distance = 16 m. Displacement = 8 m north.
A walker goes 30 m in 6 s, rests for 4 s, then walks 20 m in 5 s. Find average speed for the entire trip.
total distance = 50 m; total time = 15 s; average speed ≈ 3.33 m/s.
A straight graph segment goes from (2 s, 5 m) to (7 s, 20 m). Calculate its speed.
Change in distance = 15 m; change in time = 5 s; speed = 3 m/s.
A sled is pulled with 16 N right and 7 N left, while another person pushes 5 N right. Find its net force.
16 + 5 − 7 = 14 N right.
A 10 kg crate experiences 30 N of net force to the left. Find its acceleration and name the law.
3 m/s² left, Newton's Second Law.
Two robots start at the same point and end at the same point. Robot A travels 20 m; Robot B travels 45 m. Compare their distances and displacements.
Their distances differ (20 m and 45 m), but both displacements are zero.
A robot travels 12 m east and 4 m west in 4 s. Find average speed AND average velocity.
Distance = 16 m, so average speed = 4 m/s. Displacement = 8 m east, so average velocity = 2 m/s east.
A distance-time graph first rises steeply, then becomes horizontal, then rises gently. Describe the object's motion in order and compare the two moving speeds.
Moving faster at a constant speed, then stopped, then moving at a slower constant speed.
An object is moving left but has a net force to the right. Can it still be moving left? What happens to its velocity?
Yes. It may still move left while slowing down; its acceleration points right.
Two skaters push off each other. Skater A has twice the mass of B. Compare the force on each and explain why their accelerations differ.
Third Law: equal, opposite forces on different skaters. Second Law: lighter skater B has greater acceleration.