Q: Convert a speed of 120 inch/minute to meter/second.

$$120\ \mathrm{in/min} \times \frac{0.0254\ \mathrm{m}}{1\ \mathrm{in}} \times \frac{1}{60\ \mathrm{s}} = 0.0508\ \mathrm{m/s}$$

Q: A velocity-time plot shows a constant velocity of $$5\ \mathrm{m/s}$$ for 10 seconds. What is the total displacement?

$$5\ \mathrm{m/s} \times 10\ \mathrm{s} = 50\ \mathrm{m}$$

Q: A ball is thrown vertically upward with an initial speed of $$20\ \mathrm{m/s}. $$What is the maximum height reached? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

$$h = \frac{v^2$}{2g} = \frac{(20)^2$}{2 \times 9.8} = 20.4\ \mathrm{m}$$

Question 1

Which of the following best describes a 'discrepant event' in the context of scientific investigations?

Accepted Answer

An event that contradicts or challenges students' expectations, prompting further inquiry.

Question 2

A student proposes the hypothesis: 'If a ball is dropped from a height, it will accelerate due to gravity.' Which characteristic makes this a testable hypothesis?

Accepted Answer

It can be measured and observed through experimentation.

Question 3

Which of the following is the correct sequence of steps in the scientific process?

Accepted Answer

Observation, Hypothesis, Experiment, Analysis, Conclusion

Question 4

Which tool would best measure the inertia of translation for a moving cart?

Accepted Answer

A balance

Question 5

An object is moving in a straight line and suddenly the force acting on it is removed. According to Newton's First Law, what path will the object follow?

Accepted Answer

It will continue in a straight line at constant velocity.

Question 6

Which of the following units is used to measure inertia of translation?

Accepted Answer

$$\mathrm{kg}$$

Question 7

A measuring instrument shows readings between 2.0 cm and 2.2 cm. What is the uncertainty of the instrument if the smallest division is 0.1 cm?

Accepted Answer

$$\pm 0.1\ \mathrm{cm}$$

Question 8

A car travels 30 miles at 60 mph, then 20 miles at 40 mph. What is the average speed for the entire trip?

Accepted Answer

$$\frac{50\ \mathrm{miles}}{\frac{30}{60} + \frac{20}{40}\ \mathrm{hours}} = 48\ \mathrm{mph}$$

Question 9

Convert a speed of 120 inch/minute to meter/second.

Accepted Answer

$$120\ \mathrm{in/min} 	imes \frac{0.0254\ \mathrm{m}}{1\ \mathrm{in}} 	imes \frac{1}{60\ \mathrm{s}} = 0.0508\ \mathrm{m/s}$$

Question 10

A velocity-time plot shows a constant velocity of $$5\ \mathrm{m/s}$$ for 10 seconds. What is the total displacement?

Accepted Answer

$$5\ \mathrm{m/s} 	imes 10\ \mathrm{s} = 50\ \mathrm{m}$$

Question 11

A ball is thrown vertically upward with an initial speed of $$20\ \mathrm{m/s}. $$What is the maximum height reached? (Assume $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$h = \frac{v^2$}{2g} = \frac{(20)^2$}{2 	imes 9.8} = 20.4\ \mathrm{m}$$

Question 12

A 2 kg object is acted upon by a net force of 10 N. What is its acceleration?

Accepted Answer

$$a = \frac{F}{m} = \frac{10}{2} = 5\ \mathrm{m/s^2$}$$

Question 13

A falling object reaches terminal velocity when the drag force equals its weight. If drag force is $$F_d = k v$$, what is the terminal velocity?

Accepted Answer

$$v_t = \frac{mg}{k}$$

Question 14

Which of the following pairs represents an action-reaction interaction according to Newton's Third Law?

Accepted Answer

Earth pulls on a falling apple; the apple pulls on Earth.

Question 15

A 3 kg object moving at $$4\ \mathrm{m/s}$$ collides with a stationary 2 kg object. If they stick together, what is their final velocity?

Accepted Answer

$$v_f = \frac{3 	imes 4 + 2 	imes 0}{3 + 2} = 2.4\ \mathrm{m/s}$$

Question 16

A force of $$10\ \mathrm{N}$$ acts on a 2 kg object for $$5\ \mathrm{s}. $$What is the change in velocity?

Accepted Answer

$$\Delta v = \frac{F 	imes t}{m} = \frac{10 	imes 5}{2} = 25\ \mathrm{m/s}$$

Question 17

Why are work and energy measured in the same SI units?

Accepted Answer

Both represent the transfer of energy and are measured in $$\mathrm{J} ($$joules), where $$1\ \mathrm{J} = 1\ \mathrm{N} \cdot \mathrm{m}.$$

Question 18

A machine does $$500\ \mathrm{J} of $$useful work and consumes $$800\ \mathrm{J} of $$energy. What is its efficiency?

Accepted Answer

$$	ext{Efficiency} = \frac{500}{800} 	imes 100\% = 62.5\%$$

Step-by-Step Study Guidance for Elementary Physics I (PHYS-1405-8)

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