Question

lo. swbat investigate the cause - and - effect relationship between balanced and unbalanced forces on the state of motion of objects.
dol: given a set of problems, students will investigate the cause - and - effect relationship between balanced and unbalanced forces on the state of motion of objects in at least 4 of 5 questions correctly.
1 which of the following statements is the main difference between balanced and unbalanced forces?
a. unbalanced forces are only present in moving objects, while balanced forces are always present in stationary objects.
b. balanced forces lead to no change in motion, whereas unbalanced forces lead to motion.
c. balanced forces are larger than unbalanced forces.
d. unbalanced forces occur only when objects collide.
2 a ball is shown at rest at point 1 and rolling down the ramp at point 2.
the ball is moving because a(n)______ is acting on the ball from point 1 to point 2.
a. mass
b. inertia
c. balanced force
d. unbalanced force

Explanation:

• Question 1:
• Option A: Incorrect. Balanced forces can be on moving objects (constant - velocity motion) and unbalanced forces can act on objects that are starting to move (not just during collision).
• Option B: Correct. According to Newton's first law, when forces are balanced (\(\sum F = 0\)), there is no acceleration (\(a = 0\)), so no change in motion. When forces are unbalanced (\(\sum F

eq0\)), there is an acceleration, which means a change in motion (either start moving, stop moving, or change velocity).

• Option C: Incorrect. The magnitude comparison between balanced and unbalanced forces is not the main difference. Balanced forces have \(F_{net}=0\) and unbalanced forces have \(F_{net}

eq0\), regardless of the individual force magnitudes.

• Option D: Incorrect. Unbalanced forces can act on objects in many situations, not just when they collide (e.g., a falling object has an unbalanced force due to gravity).
• Question 2:
• Option A: Incorrect. Mass is a property of an object (\(m\)), not a cause of motion. The relationship \(F = ma\) shows that force (not mass) causes acceleration.
• Option B: Incorrect. Inertia is the tendency of an object to resist changes in its state of motion. It is related to mass (\(I = m\)), but it does not cause the ball to move down the ramp.
• Option C: Incorrect. If there were a balanced force (\(F_{net}=0\)), the ball would either remain at rest (if initially at rest) or move with a constant velocity (if already in motion). But the ball is accelerating down the ramp.
• Option D: Correct. The ball is accelerating (changing its state of motion from rest at Point 1 to moving at Point 2). According to Newton's second law (\(F_{net}=ma\)), when \(a

eq0\), \(F_{net}
eq0\), which means an unbalanced force is acting on the ball (in this case, the component of gravitational force along the ramp minus frictional forces).

Answer:

1. B. Balanced forces lead to no change in motion, whereas unbalanced forces lead to motion.
2. D. unbalanced force