Motion Basics
Define the term that means "the rate at which distance is covered."
speed.
What is a force? Give a short definition.
push or pull
Which word describes "a force that opposes motion between two touching surfaces"?
Friction
What is the name for speed that also includes a direction?
Velocity
Two teams pull a rope with 60 N60 N left and 60 N60 N right. What is the net force and what will happen?
Net force = 0 N; the forces are balanced, so the rope does not move (neglecting other effects).
A cart with wheels moves across a sidewalk. Which type of friction acts on the wheels?
Rolling Friction
A ball is dropped and falls 0.3 m in 0.25 s. What measurement can we find with this information?
Speed
From which reference point would a student riding in a wagon appear to be moving: the wagon or the sidewalk? Explain briefly.
Sidewalk (the ground) — motion is measured relative to a reference frame that is not moving (the ground).
Which of Newton’s laws explains why plates mostly stay in place when a tablecloth is pulled quickly from beneath them? Name the law (by short name or number).
inertia or Newton's 1st law
Why does a feather fall more slowly than a baseball when dropped in air? Give the correct physical reason.
Air resistance
A cyclist travels 10 km in 2 hours. What is the cyclist’s average speed? Show the calculation.
5km/s must have the unit or no credit.
Use the idea of inertia to explain why the plates stayed on the table when the tablecloth was pulled quickly. (2–3 sentences)
The plates tend to remain at rest because of inertia; the tablecloth is pulled quickly so there is little horizontal force on the plates, so they remain in place.
Which statement is the general rule about gravity?
Gravity acts between any two objects with mass
Calculate the average speed between t=0.25s D=.3m and t=0.5s D=1.2m. (show work).
s1= .3/.25=1.2m/s
s2= 1.2/.5=2.4m/s
so, 1.2+2.4=3.6/2=1.8m/s
Explain why the statement "My velocity during the race was 6 m/s6 m/s." might be incomplete or incorrect. Give one clear reason.
The direction is not mentioned.
If the same force is applied to a heavier object, what happens to its acceleration? Explain using Newton’s second law (brief).
Acceleration decreases for a heavier object when the same force is applied (since a=F/ma=F/m).
A large boulder will not move even when several people push it. What type of friction is most responsible for keeping it in place? Explain why this friction can be large.
Static friction (maximum static friction) — static friction can be large when contact forces and normal force are large, preventing motion until applied force exceeds the static friction limit.