12.4.A.1Multiple Choice
Three ropes pull on a ring: one exerts 50 N east, another exerts 30 N east, and a third exerts 20 N west. What is the net force on the ring?
Select A, B, C, or D to check your answer.
Directions:Work each problem on your own paper first. For multiple choice, select A, B, C, or D. You will see right away whether you are correct. If you miss, you will see the most likely reason, and you can try again. For short response, type your answer, then compare it with the model solution. Questions mix the essential knowledge threads of Topic 2.4 — net force as the vector sum of all forces, translational equilibrium (ΣF = 0), Newton's first law (zero net force means no change in velocity, which includes staying at rest), how forces can be balanced in one direction while unbalanced in a perpendicular direction, and what makes a reference frame inertial or noninertial.
Three ropes pull on a ring: one exerts 50 N east, another exerts 30 N east, and a third exerts 20 N west. What is the net force on the ring?
Select A, B, C, or D to check your answer.
Two tugboats pull a barge: one pulls with 4000 N due east, and the other pulls with 3000 N due north (perpendicular to the first). Find the magnitude of the net force on the barge.
A ring has four forces acting on it: 10 N right, 10 N left, 5 N up, and 5 N down. What is the net force on the ring?
Select A, B, C, or D to check your answer.
A system has exactly two forces acting on it: 60 N north and 80 N east. Find the magnitude of the net force, and the angle it makes relative to east.
A sign hangs motionless from two cables attached to the ceiling at different angles. Which statement must be true about the forces acting on the sign?
Select A, B, C, or D to check your answer.
A box is held at rest on an incline by a rope parallel to the incline's surface, with friction also present. List the forces acting on the box, and state the two equilibrium conditions that must both hold.
A crate is pushed across a floor at constant velocity by a horizontal force, while friction opposes the motion. Which statement correctly describes the push force and friction during this constant-velocity motion?
Select A, B, C, or D to check your answer.
A traffic light of weight W hangs in equilibrium from two cables, cable 1 making angle θ₁ with the horizontal and cable 2 making angle θ₂ with the horizontal on the opposite side. Write the two equilibrium equations relating T₁, T₂, θ₁, θ₂, and W.
A satellite drifts through deep space, far from any significant gravitational influence, moving at a constant velocity. Which statement correctly explains this motion using Newton's first law?
Select A, B, C, or D to check your answer.
A heavy crate sits at rest on a loading dock. Explain why this is consistent with Newton's first law, and identify the two forces whose relationship makes this true.
A spacecraft's engines are turned completely off while it coasts through interstellar space, with negligible gravitational forces from distant stars. According to Newton's first law, what happens to its velocity?
Select A, B, C, or D to check your answer.
A physics student claims that "an object with zero net force on it must have zero individual forces acting on it." Explain why this claim is incorrect, using a specific example.
A skier moves down a frictionless slope, speeding up as she descends. Which statement correctly describes the forces perpendicular to and along the slope's surface?
Select A, B, C, or D to check your answer.
A ball is thrown at an angle above the horizontal and undergoes projectile motion, with air resistance ignored. Identify which direction (horizontal or vertical) is balanced and which is unbalanced, and describe the resulting velocity behavior in each.
A car drives over the top of a small hill at constant speed, where the road briefly curves downward (convex) at that point. Which statement best completes the description of the forces acting on the car exactly at the top of the hill?
Select A, B, C, or D to check your answer.
A puck undergoes uniform circular motion on frictionless ice, attached by a string anchored at the center, moving at constant speed. Identify which direction is balanced and which is unbalanced, and explain what provides the unbalanced force.
Which of the following best defines an inertial reference frame?
Select A, B, C, or D to check your answer.
An astronaut inside a spinning space station feels pressed outward against the station's inner wall. Explain why the interior of the spinning station is a noninertial reference frame, referencing what an observer there would conclude about Newton's first law.
A physics student argues that since Earth's surface is technically accelerating (due to its rotation and orbit), every physics problem solved on Earth's surface must account for this noninertial motion. Which statement best addresses this argument?
Select A, B, C, or D to check your answer.
Explain how an observer could use a single object with a known zero net force acting on it to test whether their current reference frame is inertial or noninertial.