Q: A drone is flying horizontally at 80 m/s and drops a package from a height of 180 m. Neglecting air resistance, how far horizontally does the package travel before hitting the ground? (Use $$g = 10\ \mathrm{m/s^2$})$$

$$x = v t = 80 \times 6 = 480\ \mathrm{m}$$

Q: A box of mass $$m = 12\ \mathrm{kg} is $$pushed across a frictionless floor and moves 5 meters in 2 seconds starting from rest. What is the horizontal force applied to the box?

$$F = m a = 12 \times 2.5 = 30\ \mathrm{N}$$

Q: A hot air balloon starts from rest and rises with constant acceleration. After $$t = 3.1\ \mathrm{s}$$, it is at a height of $$y = 95\ \mathrm{m}. $$What is the acceleration?

$$a = \frac{2y}{t^2$} = \frac{2 \times 95}{(3.1)^2$} = 19.8\ \mathrm{m/s^2$}$$

Q: A package is dropped from a drone at a height of 180 m. How long does it take to reach the ground? (Use $$g = 10\ \mathrm{m/s^2$})$$

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 \times 180}{10}} = 6\ \mathrm{s}$$

Q: A car travels with a constant velocity of 30 m/s for 10 seconds. What is the displacement?

$$x = v t = 30 \times 10 = 300\ \mathrm{m}$$

Question 1

A car accelerates uniformly from rest to a velocity of 20 m/s in 5 seconds. What is the acceleration of the car?

Accepted Answer

$$a = \frac{v - v_0$}{t} = \frac{20 - 0}{5} = 4\ \mathrm{m/s^2$}$$

Question 2

Which of the following is the correct SI unit for force?

Accepted Answer

$$\mathrm{kg\cdot m/s^2$}$$

Question 3

A drone is flying horizontally at 80 m/s and drops a package from a height of 180 m. Neglecting air resistance, how far horizontally does the package travel before hitting the ground? (Use $$g = 10\ \mathrm{m/s^2$})$$

Accepted Answer

$$x = v t = 80 	imes 6 = 480\ \mathrm{m}$$

Question 4

A box of mass $$m = 12\ \mathrm{kg} is $$pushed across a frictionless floor and moves 5 meters in 2 seconds starting from rest. What is the horizontal force applied to the box?

Accepted Answer

$$F = m a = 12 	imes 2.5 = 30\ \mathrm{N}$$

Question 5

Which of the following equations correctly represents Newton’s Second Law in vector form?

Accepted Answer

$$\sum \vec{F} = m \vec{a}$$

Question 6

A hot air balloon starts from rest and rises with constant acceleration. After $$t = 3.1\ \mathrm{s}$$, it is at a height of $$y = 95\ \mathrm{m}. $$What is the acceleration?

Accepted Answer

$$a = \frac{2y}{t^2$} = \frac{2 	imes 95}{(3.1)^2$} = 19.8\ \mathrm{m/s^2$}$$

Question 7

A vector $$\vec{Q} = 8\hat{i} - 6\hat{j} N is $$acting on an object. What is the magnitude of this force?

Accepted Answer

$$|\vec{Q}| = \sqrt{8^2$ + (-6)^2$} = 10\ \mathrm{N}$$

Question 8

A football is kicked to maximize its horizontal range. At what angle should it be kicked?

Accepted Answer

$$	heta = 45^\circ$$

Question 9

Which of the following quantities has the dimensions of length $$[L]$$?

Accepted Answer

$$\frac{\Delta v^2$}{a}$$

Question 10

A package is dropped from a drone at a height of 180 m. How long does it take to reach the ground? (Use $$g = 10\ \mathrm{m/s^2$})$$

Accepted Answer

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 	imes 180}{10}} = 6\ \mathrm{s}$$

Question 11

A person walks 50 m east, then 70 m at $$30^\circ$$ north of east, and finally 40 m due south. What is the $$y-$$component of the second displacement?

Accepted Answer

$$70 \sin 30^\circ = 35\ \mathrm{m}$$

Question 12

Which of the following is the correct formula for the magnitude of the kinetic friction force?

Accepted Answer

$$f_k = \mu_k n$$

Question 13

A physics professor places his cellphone on a flat table. Which forces act on the phone?

Accepted Answer

Weight and Normal Forces

Question 14

Which equation gives the acceleration in uniform circular motion?

Accepted Answer

$$a_{rad} = \frac{v^2$}{R}$$

Question 15

A car travels with a constant velocity of 30 m/s for 10 seconds. What is the displacement?

Accepted Answer

$$x = v t = 30 	imes 10 = 300\ \mathrm{m}$$

Question 16

Which of the following is the correct formula for the $$x-$$component of the cross product $$\vec{C} = \vec{A} 	imes \vec{B}$$?

Accepted Answer

$$C_x = A_y B_z - A_z B_y$$

Question 17

A block slides on a horizontal surface with friction. Which equation gives the maximum static friction force?

Accepted Answer

$$f_s \leq (f_s)_{max} = \mu_s n$$

Question 18

A person walks 50 m east, then 70 m at $$30^\circ$$ north of east, and finally 40 m due south. What is the magnitude of the resultant displacement?

Accepted Answer

$$\sqrt{(50 + 70 \cos 30^\$$circ)^2$$ + (70 \sin 30^\circ - 40)^2$} \approx 97.6\ \mathrm{m}$$

Physics Midterm Study Guidance: Units, Vectors, Newton's Laws, Kinematics, and 2D Motion

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