Q: A rocket launches vertically (as shown in the image). If the rocket's velocity vector is $$\textbf{v}$$ and the acceleration due to gravity is $$\textbf{g}$$, which equation describes its motion after launch?

$$\textbf{v}(t) = \textbf{v}_0 - \textbf{g}t$$

Q: If a vector $$\textbf{B}$$ has a magnitude of $$8$$ and points at an angle $$\theta = 60^\circ$$ from the x-axis, what is the y-component $$B_y$$?

$$B_y = 8 \sin 60^\circ = 8 \times \frac{\sqrt{3}}{2} = 4\sqrt{3}$$

Q: If a microorganism rotates its flagella at $$18,000$$ RPM, what is the angular velocity in radians per second?

$$\omega = 18,000 \times \frac{2\pi}{60} \approx 1,884$$ rad/s

Question 1

Which of the following best describes the primary goal of PHY 121 as stated in the course materials?

Accepted Answer

To apply a small set of fundamental physical principles to a wide variety of physical situations.

Question 2

A car crash test (as shown in the provided image) is an example of which fundamental physics principle?

Accepted Answer

Conservation of momentum

Question 3

If a vector $$	extbf{A}$$ has components $$A_x = 3$$ and $$A_y = 4$$, what is the magnitude of $$	extbf{A}$$?

Accepted Answer

$$\sqrt{3^2$ + 4^2$} = 5$$

Question 4

Which of the following is NOT a course goal for PHY 121?

Accepted Answer

Memorize every equation without understanding its application.

Question 5

A rocket launches vertically (as shown in the image). If the rocket's velocity vector is $$	extbf{v}$$ and the acceleration due to gravity is $$	extbf{g}$$, which equation describes its motion after launch?

Accepted Answer

$$	extbf{v}(t) = 	extbf{v}_0 - 	extbf{g}t$$

Question 6

Which of the following best illustrates the concept of power-to-weight ratio as discussed in the lecture?

Accepted Answer

Comparing the speed of E. coli to a cheetah and an F1 engine.

Question 7

If a microorganism moves 15 times its body length per second and its body length is $$10 \mu m$$, what is its speed?

Accepted Answer

$$150 \mu m/s$$

Question 8

Which vector operation is used to find the component of a force in a particular direction?

Accepted Answer

Dot product

Question 9

A student models the motion of planets in the solar system (as shown in the image). Which fundamental principle is most relevant?

Accepted Answer

Newton's law of universal gravitation

Question 10

If a vector $$	extbf{B}$$ has a magnitude of $$8$$ and points at an angle $$	heta = 60^\circ$$ from the x-axis, what is the y-component $$B_y$$?

Accepted Answer

$$B_y = 8 \sin 60^\circ = 8 	imes \frac{\sqrt{3}}{2} = 4\sqrt{3}$$

Question 11

Which of the following is a plausible reason for making approximations and idealizations in physics modeling?

Accepted Answer

To simplify complex systems so fundamental principles can be applied effectively.

Question 12

A cheetah runs at a speed comparable to E. coli's relative speed. If a cheetah's body length is $$1.5 m $$and it runs $$15$$ times its body length per second, what is its speed?

Accepted Answer

$$22.5 m/s$$

Question 13

Which digital tool is NOT used for course communication in PHY 121?

Accepted Answer

Email

Question 14

If a vector $$	extbf{C} is $$given by $$	extbf{C} = 2\hat{i} + 3\hat{j}$$ and another vector $$	extbf{D} = -\hat{i} + 4\hat{j}$$, what is $$	extbf{C} + 	extbf{D}$$?

Accepted Answer

$$\hat{i} + 7\hat{j}$$

Question 15

Which scenario best illustrates the application of Newtonian mechanics in biological physics?

Accepted Answer

Modeling microorganism propulsion using force and motion equations.

Question 16

A student is asked to find the resultant of two vectors: $$	extbf{A} = 5\hat{i}$$ and $$	extbf{B} = 12\hat{j}. $$What is the magnitude of the resultant vector?

Accepted Answer

$$\sqrt{5^2$ + 12^2$} = 13$$

Question 17

Which of the following is a plausible misconception about vectors?

Accepted Answer

Vectors can be added by simply adding their magnitudes.

Question 18

If a microorganism rotates its flagella at $$18,000$$ RPM, what is the angular velocity in radians per second?

Accepted Answer

$$\omega = 18,000 	imes \frac{2\pi}{60} \approx 1,884$$ rad/s

Question 19

Which of the following best describes the importance of learning the technical language of Newtonian physics?

Accepted Answer

It allows students to communicate and understand physical concepts precisely.

Introduction to Physics and Vectors – PHY 121 Study Notes

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