Physics and units
What does physics study? A) Only motion B) Matter, energy, motion, forces, and their interactions C) Only living organisms D) Only chemicals
B
A cyclist travels 120 m in 20 s. What is the cyclist’s average speed?
6 m/s
Approximately how many centimeters are in 1 inch?
2.54 cm
Write 5,478,000 in scientific notation.
5.48× 10^6
Name three branches of physics.
Possible answers: mechanics, thermodynamics, optics, electromagnetism, acoustics, quantum physics, nuclear physics, etc.
“Physics is only about things moving.” Is this statement correct?
No. Physics studies matter, energy, motion, forces, interactions, and many other physical phenomena.
A cyclist travels 4.5 km at a constant velocity of 6 m/s. How long does it take to complete the trip?
4.5 km = 4,500 m
Convert 10 inches to centimeters. Use 1 in = 2.54 cm.
25.4 cm
Write 0.00000032 in scientific notation.
3.2 × 10^-7
Which branch of physics studies motion, forces, and the behavior of objects?
Mechanics.
What is the most widely used measurement system in science?
The International System of Units (SI).
A runner travels at a speed of 12 ft/s for 3 minutes. How far does the runner travel?
Answer: 2,160 ft = 720 yd
A person is 5 feet 6 inches tall. Convert their height to centimeters. Use 1 ft = 12 in and 1 in = 2.54 cm.
5 ft = 60 in; + 6 = 66 in → 167.64 cm
Write 6.7 × 10^11 in ordinary decimal notation.
670,000,000, 000
Which branch of physics is most directly involved in studying light, lenses, mirrors, and cameras?
Optics.
`Which situation is NOT primarily related to physics?
A) A cyclist slowing down by applying the brakes
B) A mirror reflecting light
C) Water boiling as its temperature increases
D) A plant producing glucose through photosynthesis
D
A car travels 2.5 miles in 6 minutes. What is its average speed in meters per second (m/s)?
Use: 1 mile = 1,609 m
Answer: ≈ 11.18 m/s
A car is traveling at 60 miles per hour. Using 1 mile ≈ 1.609 km, approximately how fast is it traveling in km/h?
60 × 1.609 = 96.54 km/h
Which number is greater: 4.5 × 10^-3 or 8.2 × 10^-2? How do you know?
8.2 × 10⁻² is greater.
Since −2 is greater than −3, the number with 10⁻² is greater.
To visualize it:
A company is designing a smartphone camera. Name at least two branches of physics that could be involved and explain how.
Optics → lenses and light; electromagnetism/electronics → sensors, electrical signals, and circuits.
A kilometer, meter, min, pounds, ampere and Fahrenheit, are all SI base units. Is it true? Explain.
False. Only the meter (m) and ampere (A) are SI base units.
A motorcycle is traveling at 25 m/s. The rider applies the brakes, and the motorcycle slows to 10 m/s in 5 s. What is its acceleration?
a=-3m/s2
A package has a mass of 10 lb. Using 1 lb ≈ 0.4536 kg, what is its mass in kilograms? If a machine can carry a maximum of 4.5 kg, can it safely carry the package?
10 × 0.4536 = 4.536 kg. No, it slightly exceeds the 4.5 kg limit.
A scientist measures the diameter of a cell as 3.75 X 10 ^-7 m. Express this measurement in scientific notation.
0.000000375
Engineers are designing an electric car. Name at least three branches of physics that could be applied during its design and explain what each contributes.
Mechanics → motion, forces, braking, suspension; electromagnetism → electric motor and circuits; thermodynamics → heat, battery temperature, and energy efficiency. Other valid answers could include materials/solid-state or fluid dynamics depending on the design aspect.