Question

calculating net force
for each example, (1) identify the direction (same or opposite) that the main forces are acting on the object,
(2) the method to calculate net force (add or subtract), (3) calculate the net force, and (4) identify if forces are
balanced or unbalanced. be sure to include your unit, newtons (n).
diagrams: hot air balloon (less dense air 5000 n up, gravity 4000 n down); box with two people (person pulling box 75 n left, person pushing box 100 n left); bowling ball (ball rolling 60 n right, friction 10 n left); two people pulling rope (person pulling 90 n left, person pulling 90 n right); ball hitting bat (ball hitting bat 70 n down, swing 150 n up); airplane (air resistance 800 n left, engine thrust 2200 n right). each diagram has 4 answer boxes.

Explanation:

First Example (Hot Air Balloon)

Step1: Identify direction

Forces (less dense air upward, gravity downward) act in opposite directions.

Step2: Determine method

Since directions are opposite, subtract the smaller force from the larger.

Step3: Calculate net force

Net force = \( 5000\,\text{N} - 4000\,\text{N} = 1000\,\text{N} \) (upward, as 5000 N > 4000 N).

Step4: Identify balanced/unbalanced

Forces are unbalanced (net force ≠ 0).

Step1: Identify direction

Both forces (pulling 75 N left, pushing 100 N left) act in the same direction.

Step2: Determine method

Since directions are same, add the forces.

Step3: Calculate net force

Net force = \( 75\,\text{N} + 100\,\text{N} = 175\,\text{N} \) (leftward).

Step4: Identify balanced/unbalanced

Forces are unbalanced (net force ≠ 0).

Step1: Identify direction

Forces (ball rolling 60 N right, friction 10 N left) act in opposite directions.

Step2: Determine method

Since directions are opposite, subtract the smaller force from the larger.

Step3: Calculate net force

Net force = \( 60\,\text{N} - 10\,\text{N} = 50\,\text{N} \) (rightward, as 60 N > 10 N).

Step4: Identify balanced/unbalanced

Forces are unbalanced (net force ≠ 0).

Answer:

1. Opposite
2. Subtract
3. \( 1000\,\text{N} \) (upward)
4. Unbalanced

Second Example (Box with Two People)