NEWTON’S LAWS & MOMENTUM
State Newton’s First Law.
An object at rest stays at rest and an object in motion stays in motion unless acted upon.
Write the formula for work.
W=Fd
Convert 6 ft → m.
6 ft×0.3048 m/ 1 ft=1.8288 m
Define a “scientific fact.”
A scientific fact is a statement supported by repeated observation and experiment and accepted as correct as far as we currently know.
What color were stop signs before they were red?
yellow
Mass = 0.25 kg, velocity = 30 m/s.
Calculate momentum.
m=0.25 kg, v=30 m/s
p=mv=0.25×30=7.5 kg·m/s
p=7.5 kg·m/s
If force = 90 N and distance = 3.5 m, calculate work.
F=90 N, d=3.5 m
W=Fd=90×3.5=315 J
72 in → m
≈ 1.83 m
Define “truth.”
Truth is the way things really are and does not change. It is true for all people, all times, and all places.
Which country is credited with inventing the earliest form of ice cream?
China
You push on a wall. The wall “pushes back.” Which law is this?
Newton’s Third Law.
When you push on the wall, the wall pushes back on you with an equal and opposite force.
Does holding a heavy object in place count as work?
No. In physics, work requires displacement. If the object doesn’t move, distance = 0, so W=Fd=0
30 mi/hr → m/s
13.4 m/s
Why can scientific facts change over time?
Scientific facts can change because they are based on evidence and models. When new data or better experiments come along, we may realize our previous understanding was incomplete or slightly wrong, so the “fact” is updated.
Which city hosted the first modern Olympics?
Athens
A 0.020 kg bead moves at 4.2 m/s.
A 0.040 kg bead moves at 2.1 m/s.
Which has more momentum, or are they equal?
Bead 1:
p1=0.020×4.2= 0.084 kg·m/s
Bead 2:
p2=0.040×2.1 =0.084 kg·m/s
They have equal momentum.
A crate weighing 4100 lb is lifted 1.85 m.
Calculate the work done.
(Use 1 lb = 4.45 N.)
Weight: 4100 lb
Convert to newtons:
Fw=4100×4.45=18,245 N
Work lifting 1.85 m:
W=Fd=18,245×1.85≈33,753 J
0.072 kg → g
72 g
Why did early scholars resist heliocentrism?
Many early scholars were committed to the older geocentric model. They felt like a threat to their beliefs rather than just a new scientific explanation.
What animal laughs when it’s tickled?
A rat
A 4.0 kg object has a net force of 14 N acting on it.
What is its acceleration?
a=F/m=14 N/4.0 kg=3.5 m/s^2
A 0.75 kg object is lifted to a height of 4.2 m.
Calculate gravitational potential energy.
m=0.75 kg, h=4.2 m, g=9.8 m/s^2
Eg=mgh=0.75×9.8×4.2=30.87 J
12,500 lb → N
5.56 × 10⁴ N
Explain the difference between scientific interpretation and unchanging truth.
Scientific interpretation = how we understand data, experiments, and models (which can improve and change).
Unchanging truth = reality that does not change, even when our scientific models adjust.
The difference matters because when a scientific model shifts, it doesn’t mean truth itself has changed, only our interpretation of the world has.
How long is the longest hiccuping streak ever recorded?
68 years