--- title: "AP Physics 1 Unit 4 Practice Test" description: "A timed AP Physics 1 Unit 4 (Linear Momentum) practice test in the AP format, drawn from 794 multiple-choice questions and 42 FRQs written for the unit. The standard version takes about 88 minutes." canonical: "https://fiveable.me/ap-physics-1-revised/unit-test/4" type: "unit-test" subject: "AP Physics 1" unit: "Unit 4" --- # AP Physics 1 Unit 4 Practice Test ## Overview A timed AP Physics 1 Unit 4 (Linear Momentum) practice test in the AP format, drawn from 794 multiple-choice questions and 42 FRQs written for the unit. The standard version takes about 88 minutes. ## Test Format - 20 Multiple Choice Questions (40 minutes) - 1 FRQ – FRQ 1 – Mathematical Routines (24 minutes) - 1 FRQ – FRQ 2 – Translation Between Representations (24 minutes) ## Unit FRQs by Type - [FRQ 1 – Mathematical Routines](/ap-physics-1-revised/frqs/mathematical-routines?unit=4): 5 questions - [FRQ 2 – Translation Between Representations](/ap-physics-1-revised/frqs/translation-between-representations?unit=4): 9 questions - [FRQ 3 – Experimental Design](/ap-physics-1-revised/frqs/experimental-design?unit=4): 9 questions - [FRQ 4 – Qualitative/Quantitative Translation](/ap-physics-1-revised/frqs/qualitative-quantitative-translation?unit=4): 19 questions ## Practice Questions ### Question 1 A 0.40 kg ball falls vertically and hits the floor with a speed of 5.0 m/s, rebounding upward with a speed of 3.0 m/s. If the ball is defined as the system, what is the magnitude of the change in momentum of the system during the collision? - (A) 0.80 kg·m/s - (B) 2.0 kg·m/s - (C) 3.2 kg·m/s - (D) 8.0 kg·m/s **Answer: (C)** Calculates the change in velocity as final minus initial ($$3 - (-5) = 8$$ m/s) and multiplies by mass ($$0.40 \times 8$$). ### Question 2 Cart A (2.0 kg) moving right at 3.0 m/s collides with Cart B (1.0 kg) moving left at 2.0 m/s. If the system consists of both carts and friction is negligible, what is the magnitude of the total momentum of the system after the collision? - (A) 1.0 kg·m/s - (B) 4.0 kg·m/s - (C) 6.0 kg·m/s - (D) 8.0 kg·m/s **Answer: (B)** Sums the initial momenta vectors ($$2(3) + 1(-2) = 4$$) and recognizes that total momentum is conserved for the two-cart system. ### Question 3 A 5.0 kg box slides across a horizontal surface with an initial speed of 4.0 m/s. A constant friction force of 10 N acts on the box opposite to its motion. If the box is the system, what is the magnitude of its momentum 1.5 seconds later? - (A) 5.0 kg·m/s - (B) 15 kg·m/s - (C) 20 kg·m/s - (D) 35 kg·m/s **Answer: (A)** Calculates initial momentum ($$20$$), subtracts the impulse from friction ($$10 \times 1.5 = 15$$), resulting in $$5$$. ### Question 4 A 3.0 kg object moves north at 4.0 m/s, and a 2.0 kg object moves south at 6.0 m/s. What is the magnitude of the velocity of the center of mass of the two-object system? - (A) 0 m/s - (B) 2.4 m/s - (C) 4.8 m/s - (D) 5.0 m/s **Answer: (A)** Calculates total momentum ($$12 - 12 = 0$$), which implies the center of mass velocity is zero. ### Question 5 A cannon of mass 500 kg fires a projectile of mass 10 kg horizontally at a speed of 200 m/s. If the cannon and projectile are defined as the system and friction is negligible, what is the recoil speed of the cannon? - (A) 0.25 m/s - (B) 4.0 m/s - (C) 20 m/s - (D) 40 m/s **Answer: (B)** Sets initial momentum to zero and equates the magnitude of cannon and projectile momenta ($$500v = 10 \times 200$$). ### Question 6 A 2.0 kg rock is thrown vertically upward. Consider the rock alone as the system. Between the time it is thrown and the time it reaches its peak 1.5 seconds later, what is the magnitude of the change in the system's momentum? (Use $$g = 10 \text{ m/s}^2$$) - (A) 15 kg·m/s - (B) 20 kg·m/s - (C) 30 kg·m/s - (D) 45 kg·m/s **Answer: (C)** Calculates the impulse provided by the external force of gravity ($$J = F_{ext}t = mgt = 2 \times 10 \times 1.5$$). ### Question 7 A net force acting on a 4.0 kg object varies with time. The force is constant at 12 N for 3.0 s, then drops instantly to zero. If the object starts from rest, what is its final speed? - (A) 3.0 m/s - (B) 9.0 m/s - (C) 12 m/s - (D) 36 m/s **Answer: (B)** Calculates impulse ($$12 \times 3 = 36$$) and divides by mass ($$36 / 4$$) to find the change in velocity. ### Question 8 Two ice skaters, mass 60 kg and 40 kg, stand together at rest on frictionless ice. They push off each other, and the 40 kg skater moves right at 3.0 m/s. If the system is defined as the 60 kg skater only, what is the magnitude of the impulse exerted on this system? - (A) 80 N·s - (B) 120 N·s - (C) 180 N·s - (D) 200 N·s **Answer: (B)** Calculates the momentum of the other skater ($$40 \times 3 = 120$$) and applies Newton's 3rd Law. ### Question 9 A 1000 kg car traveling at 20 m/s collides with a stationary 1500 kg truck. They lock bumpers and move together. Calculating the final velocity requires defining the system as both vehicles to conserve momentum. What is this final speed? - (A) 8.0 m/s - (B) 12 m/s - (C) 13 m/s - (D) 20 m/s **Answer: (A)** Equates initial momentum ($$20,000$$) to final momentum ($$2500v$$) and solves for $$v$$. ### Question 10 A 20 kg cart moves horizontally at 4.0 m/s. A 5.0 kg sandbag is dropped vertically into the cart. If the system is the cart and sandbag, horizontal momentum is conserved. What is the final speed? - (A) 3.2 m/s - (B) 4.0 m/s - (C) 5.0 m/s - (D) 16 m/s **Answer: (A)** Conserves horizontal momentum: $$20(4) = (20+5)v$$, so $$80 = 25v$$. ## Review the Unit - [4.1 Linear Momentum](/ap-physics-1-revised/unit-4/1-linear-momentum/study-guide/aEYIGw4MVE0g5Zrb) - [4.2 Change in Momentum and Impulse](/ap-physics-1-revised/unit-4/2-change-in-momentum-and-impulse/study-guide/57woWSFVbwXIjDat) - [4.3 Conservation of Linear Momentum](/ap-physics-1-revised/unit-4/3-conservation-of-linear-momentum/study-guide/B4haVeUmTXK0iRFh) - [4.4 Elastic and Inelastic Collisions](/ap-physics-1-revised/unit-4/4-elastic-and-inelastic-collisions/study-guide/ZmUQjuCAgv73jObj) ## Other Unit Tests - [Unit 1: Kinematics](/ap-physics-1-revised/unit-test/1) - [Unit 2: Force and Translational Dynamics](/ap-physics-1-revised/unit-test/2) - [Unit 3: Work, Energy, and Power](/ap-physics-1-revised/unit-test/3) - [Unit 5: Torque and Rotational Dynamics](/ap-physics-1-revised/unit-test/5) - [Unit 6: Rotating Systems: Energy & Momentum](/ap-physics-1-revised/unit-test/6) - [Unit 7: Oscillations](/ap-physics-1-revised/unit-test/7) - [Unit 8: Fluids](/ap-physics-1-revised/unit-test/8) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`)