Let's go through each problem step by step and verify the solutions. The goal is to calculate
net force and determine whether the forces are
balanced or unbalanced.
---
Problem 11: Opposite Directions
> A car has two forces acting on it:
- 10 N to the right
- 7 N to the left
a. Net force = ?
We subtract forces in opposite directions:
$$
\text{Net force} = 10\,\text{N (right)} - 7\,\text{N (left)} = 3\,\text{N to the right}
$$
✔ Correct answer:
3 N to the right
b. Balanced or unbalanced?
Since there is a net force (not zero), the forces are
unbalanced.
✔ Correct answer:
Unbalanced
---
Problem 12: Boy and Dog
> Dog pulls with 50 N to the right
> Boy pulls with 18 N backward (to the left)
a. Net force = ?
$$
\text{Net force} = 50\,\text{N (right)} - 18\,\text{N (left)} = 32\,\text{N to the right}
$$
✔ Correct answer:
32 N to the right
b. Balanced or unbalanced?
Net force ≠ 0 →
Unbalanced
✔ Correct answer:
Unbalanced
---
Problem 13: People Pulling Rope
> Left side: Two people pulling
left with 150 N each → Total = 300 N left
> Right side: One person pulls 150 N right, another pulls 200 N right → Total = 350 N right
a. Net force = ?
$$
\text{Net force} = 350\,\text{N (right)} - 300\,\text{N (left)} = 50\,\text{N to the right}
$$
✔ Correct answer:
50 N to the right
b. Balanced or unbalanced?
Net force ≠ 0 →
Unbalanced
✔ Correct answer:
Unbalanced
---
Problem 14: Forces on a Box
Forces:
- 5 N → right
- 2 N → right
- 10 N ← left
Total rightward force: $5 + 2 = 7$ N
Leftward force: 10 N
a. Net force = ?
$$
\text{Net force} = 10\,\text{N (left)} - 7\,\text{N (right)} = 3\,\text{N to the left}
$$
But in your image, you wrote:
"Net force = 10N - 7N = 3N" — this is correct in magnitude, but direction is missing.
✔ Should be:
3 N to the left
b. Balanced or unbalanced?
Yes, unbalanced because net force ≠ 0.
✔ Correct answer:
Unbalanced
---
Problem 15: Refrigerator
Two men pushing
in the same direction with 100 N each.
a. Net force = ?
$$
100\,\text{N} + 100\,\text{N} = 200\,\text{N (forward)}
$$
✔ Correct answer:
200 N
b. Balanced or unbalanced?
Net force ≠ 0 →
Unbalanced
✔ Correct answer:
Unbalanced
---
Problem 16: Frankie and Caitlin push four-wheeler
Frankie: 40 N
Caitlin: 20 N
Both pushing in the
same direction
a. Net force = ?
$$
40\,\text{N} + 20\,\text{N} = 60\,\text{N}
$$
✔ Correct answer:
60 N
b. Balanced or unbalanced?
Net force ≠ 0 →
Unbalanced
✔ Correct answer:
Unbalanced
---
✔ Final Summary of All Answers:
| Problem | Net Force | Direction | Balanced/Unbalanced |
|--------|-----------|-----------|----------------------|
| 11 | 3 N | Right | Unbalanced |
| 12 | 32 N | Right | Unbalanced |
| 13 | 50 N | Right | Unbalanced |
| 14 | 3 N | Left | Unbalanced |
| 15 | 200 N | Forward | Unbalanced |
| 16 | 60 N | Forward | Unbalanced |
---
🔍 Key Concepts:
-
Net Force = Sum of all forces in a direction (considering sign for direction).
- If net force = 0 →
Balanced forces, object doesn't accelerate.
- If net force ≠ 0 →
Unbalanced forces, object accelerates in the direction of net force.
All answers you provided are
correct, except that
Problem 14 should clearly state the direction as
left, not just "3N".
✔ Your work is excellent! Just ensure direction is always specified when needed.
Parent Tip: Review the logic above to help your child master the concept of net force worksheet with answers.
