Topic 2 What unequal forces do to motion — what needs James (16)

Topic 2 · What unequal forces do to motion · Type 1 · tests FOR5-022

EasyMCQType 1 — from two arrow lengths (text or drawn), which statement about the forces is true

Here is a force drawing of a gate with a push on each side. [drawing: the gate; left push 3 squares, right push 6 squares] Which statement about the forces on the gate is true?

1. a) The forces are equal.
2. b) The forces are unequal: the left push is stronger.
3. c) The forces are unequal: the right push is stronger. ← key
4. d) Only one force acts on it.

Why it is this type: Two opposite forces of different strengths are called unequal forces. The right push is 6 squares long and the left push is 3 squares long. So the forces are unequal, and the right push is stronger.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 2 · tests FOR5-022

EasyMCQType 2 — what a longer arrow shows; what two arrows of the same length tell you

Bodhi draws two forces on a box, and he draws one arrow longer than the other. What is he showing about that force?

1. a) It lasts longer.
2. b) It is stronger. ← key
3. c) It acts on a heavier part.
4. d) It acts faster.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 3 · tests FOR5-022

MediumMCQType 3 — which pair of opposite forces is unequal (or equal)

Here is a force drawing of a tire being pulled by two ropes, with four forces on it. [drawing: weight 4, the ground's push 4, left pull 6, right pull 2] Which pair of opposite forces is unequal?

1. a) the up and down pair
2. b) the left and right pair ← key
3. c) both pairs
4. d) neither pair

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 4 · tests FOR5-022

EasyMCQType 4 — the other name for unequal (balanced) forces

Two opposite forces of the same strength are called balanced forces. What is another name for them?

1. a) unequal forces
2. b) equal forces ← key
3. c) contact forces
4. d) friction

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 5 · tests FOR5-023

EasyMCQType 5 — what happens to the motion when the stronger force's direction is given in words

A hockey puck slides straight across the ice, and a stick taps it from the side with nothing pushing back against the tap. What happens to the puck's motion?

1. a) It speeds up.
2. b) It slows down.
3. c) It changes direction. ← key
4. d) It keeps the same speed.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 6 · tests FOR5-023

MediumMCQType 6 — what happens to the motion, read off two arrows and the direction already moving

Here is a force drawing of a lawn mower that is moving to the right. [drawing: friction left 6, the push right 1, a MOVING cue right] What happens to the lawn mower's motion?

1. a) It speeds up.
2. b) It slows down. ← key
3. c) It changes direction.
4. d) It keeps the same speed.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 7 · tests FOR5-022

HardtypedType 7 — the stronger arrow's length (medium); the difference between the two arrows, after finding the unequal pair or reading both arrows (hard); MCQ: which of two speeds up more

Here is a force drawing of a tire being pulled by two ropes, with four forces on it. Find the pair of opposite forces that is unequal. How many squares longer is the stronger arrow of that pair than the weaker one? Type the number. — 4 (4 squares, four).

Why it is this type: The weight and the ground's push are both 4 squares long, so that pair is equal. The left pull is 6 squares long and the right pull is 2 squares long, so that pair is unequal. 6 − 2 = 4 squares, so the stronger arrow is 4 squares longer.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 8 · tests FOR5-023

HardMCQType 8 — "X is wrong: what is the correct reason?" on a documented belief, or the correct reason for a stated outcome

Bodhi says only the stronger force matters, so the friction makes no difference to how much a moving object speeds up. Bodhi is wrong: what is the correct reason?

1. a) A bigger difference between the arrows makes a bigger change. ← key
2. b) Friction is always the stronger of the two forces on a moving object.
3. c) Friction always makes a moving object speed up faster.
4. d) The weaker force only makes the object change direction. Source: register FOR5 SD-2 "Only the strongest force matters"; Lesson 2 (Predict how the motion changes when the forces are unequal)'s table and its line "The weaker force still matters…".

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 9 · tests FOR5-041

MediumMCQType 9 — which of two objects, same force, changes its motion more or less

Here are force drawings of an empty suitcase and the same suitcase packed full, each getting the same push. [drawing: two outlines, the same red arrow 4 squares on each] Which suitcase's motion changes less?

1. a) the empty suitcase
2. b) the full suitcase ← key
3. c) both the same
4. d) neither one moves

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 10 · tests FOR5-041

MediumMCQType 10 — why the full one speeds up less; what is different about the loaded chair

Caleb gives the same push to an empty cooler and to the same cooler full of ice. Why does the full cooler speed up less?

1. a) Earth pulls it down and pins it to the ground.
2. b) The push on it is weaker.
3. c) It has more mass. ← key
4. d) It is bigger on the outside.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 11 · tests FOR5-041

EasyMCQType 11 — which has more mass

An empty paint can and the same can full of paint sit on a shelf. Which can has more mass?

1. a) the empty can
2. b) both have the same mass
3. c) the full can ← key
4. d) neither can has mass

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 12 · tests FOR5-023

HardMCQType 12 — what he must do to match the empty one's change; a steady cart rolls onto carpet; a gentle push on the loaded trailer against a stronger push on the empty one

A cart moves at a steady speed with a pull of 4 squares and friction of 4 squares. Then the cart rolls onto carpet, where the friction grows to 6 squares while the pull stays 4 squares. What happens to the cart's motion on the carpet?

1. a) It speeds up.
2. b) It slows down. ← key
3. c) It changes direction.
4. d) It keeps the same speed.

Recommendation: Approve as the exemplar

Topic 2 · What unequal forces do to motion · Type 13 · tests FOR5-041

HardtypedType 13 — the science word for how much stuff is in a thing, on a scene where the full one speeds up less (the 8 Oct review closed the stem: "what the full one has more of" had "weight" as a true answer)

Recommendation: Approve as the exemplar