Physics Quiz

A point is positioned at a distance R from the origin in Q1 at an angle φ with respect to the positive x-axis. What is the position of the point in unit vector notation?

• Rcosφi + Rsinφj

• -Rcosφi - Rsinφj

• Rsinφi - Rcosφj

• -Rsinφi + Rcosφj

A particle is moving in the xy-plane. At t=0s, the particle’s velocity is 2m/s in the +x-direction. At t=3s, the particle’s velocity is 6 m/s in the +y-direction. What is the average acceleration of the particle between t=0s and t=3s?

• 2 m/s² at 45 degrees above the +x-direction

• 2 m/s² at 45 degrees above the -x-direction

• 1 m/s² in the +y-direction

• 1 m/s² in the -y-direction

Tags

NGSS.HS-PS2-1

A toy car moves in the x-direction with an acceleration given by the equation a=30-3t², where t is time in seconds and a is in m/s². At t=0, the toy car is located at position x=5 m and has a velocity v=4 m/s. Which of the following correctly represents the position, x, in meters, of the toy car as a function of t?

• x = -1/2 t⁴ + 15t² + 4t + 5

• x = -1/3 t³ + 15t² + 4t + 5

• x = -1/3 t⁴ + 15t² + 4t + 5

• x = 1/2 (30 - 3t²)t² + 4t + 5

A projectile is launched from a height h₀ with an initial velocity v₀ at an angle θ to the horizontal. Which of the following expressions gives the total time the projectile is in the air before hitting the ground?

• (v₀ * sin(θ) + sqrt((v₀ * sin(θ))² + 2gh₀)) / g

• (v₀ * sin(θ) - sqrt((v₀ * sin(θ))² + 2gh₀)) / g

• (v₀ * cos(θ) + sqrt((v₀ * cos(θ))² + 2gh₀)) / g

• (v₀ * sin(θ) + sqrt((v₀ * sin(θ))² - 2gh₀)) / g

Position vectors C and D are given as C = (3î + 6ĵ)m and D = (2î + 4ĵ)m. What is C-3D in unit-vector notation form and the magnitude of this vector?

• Unit-vector Notation: (-3î - 6ĵ)m Magnitude: 6.7m

• Unit-vector Notation: (-3î - 6ĵ)m Magnitude: 9m

• Unit-vector Notation: (9î + 18ĵ)m Magnitude: 20m

• Unit-vector Notation: (9î + 18ĵ)m Magnitude: 21m

Two trains are at rest on parallel tracks. At t=0, both trains start moving in the same direction. The first train accelerates at a constant rate a₁ for a time t₁, covering a distance of D. If the second train accelerates at a constant rate of a₁/3 for a time 3t₁, what is the distance covered by the second train from 0 to 3t₁, in terms of D?

• D/3

• D

• 3D

• 9D

Tags

NGSS.HS-PS2-1

The position of a particle is given by x(t) = Dt^3 + E and y(t) = Ft^2 - G, where D = 2m/s^3, E = 1m, F = 4m/s^2, G = 3m, and t is in seconds. The magnitude of the particle’s acceleration at t = 0 and at t = 2s are a_0 and a_2, respectively. Which of the following statements about a_0 and a_2 is correct?

• a_0 = a_2

• a_0 > a_2 = 0

• 0 = a_0 < a_2 $

• 0 < a_0 < a_2

Tags

NGSS.HS-PS2-1

Two velocity vectors {u} and {w} have the same magnitude t but point in different directions. Which of the following statements correctly describes the magnitude of the vector |{u} + \{w}| ?

• A vector with magnitude zero.

• A vector with magnitude greater than zero and less than 2t.

• A vector with a magnitude equal to 2t.

• A vector with a magnitude greater than 2t.

A ball is placed on a moving conveyor belt that is traveling at a constant speed v_1 in the +x-direction. The ball is then gently pushed off the belt and falls to the ground. What is the horizontal speed of the ball with respect to the ground just before it hits the ground?

• v_1

• v_1 + v_2

• v_2

• 0

Tags

NGSS.HS-PS2-2

A swimmer wants to cross a river from point A to point B that are directly across the river from each other. The river flows with a velocity of v_river = 4 m/s in the positive x-direction relative to the riverbank, and the swimmer can swim with a velocity of v_swimmer = 8 m/s in the positive y-direction relative to the water. In which direction should the swimmer aim to reach point B directly and why?

• Upriver of Point B because the y-component of the swimmer’s velocity with respect to the water needs to be equal in magnitude to the velocity of the river.

• Upriver of Point B because the x-component of the swimmer’s velocity with respect to the water needs to be equal in magnitude to the velocity of the river but in the opposite direction.

• Toward Point B because the magnitude of the swimmer’s velocity with respect to the water is greater than the magnitude of the velocity of the river.

• Toward Point B because the y-component of the swimmer’s velocity with respect to the water is not affected by the motion of the river.

Tags

NGSS.HS-PS2-1