Let’s go through each problem one by one, using Newton’s Second Law:
Force = mass × acceleration →
F = m × a
We can also rearrange it:
- To find mass:
m = F ÷ a
- To find acceleration:
a = F ÷ m
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Problem 1:
How much force is needed to accelerate a 1000-kg car at a rate of 3 m/s²?
→ Use F = m × a
→ F = 1000 kg × 3 m/s² =
3000 N
✔ Answer:
3000, Units:
N
---
Problem 2:
If a 70-kg swimmer pushes off a pool wall with a force of 250 N, at what rate will the swimmer accelerate from the wall?
→ Use a = F ÷ m
→ a = 250 N ÷ 70 kg ≈
3.5714...
Round to 2 decimals →
3.57
✔ Answer:
3.57, Units:
m/s²
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Problem 3:
A weightlifter raises a 200-kg barbell with an acceleration of 3 m/s². How much force does the weightlifter use to raise the barbell?
→ Use F = m × a
→ F = 200 kg × 3 m/s² =
600 N
⚠️ Wait — this is tricky! The question says “raises” with acceleration. That means the lifter must overcome gravity AND provide extra force for acceleration.
But looking at the worksheet context and the triangle diagram (which only shows F = m×a), and since no mention of gravity or g=9.8 is made in any other problem, we assume they want just F = m×a as per Newton’s second law for net force causing acceleration.
So unless specified otherwise, we’ll go with simple F = m×a.
→ F = 200 × 3 =
600 N
✔ Answer:
600, Units:
N
*(Note: In real life, you’d need to add weight due to gravity too — but based on how the worksheet is set up, they’re treating this as pure F=ma without gravity added.)*
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Problem 4:
A dancer lifts his partner above his head with an acceleration of 2.5 m/s². The dancer exerts a force of 200 N. What is the mass of the partner?
→ Use m = F ÷ a
→ m = 200 N ÷ 2.5 m/s² =
80 kg
✔ Answer:
80, Units:
kg
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Problem 5:
Newton’s second law of motion states that a(n) ______ force acting on an object causes it to accelerate according to the formula net force = mass x ______. Which means the acceleration of the object is directly proportional to the ______ and inversely (oppositely) proportional to the mass.
Correct words:
- First blank:
unbalanced (because balanced forces cause no acceleration)
- Second blank:
acceleration (formula is F = m × a)
- Third blank:
force (acceleration increases if force increases)
✔ Answers:
First:
unbalanced
Second:
acceleration
Third:
force
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Problem 6:
The two factors that affect acceleration are: ______
From F = m × a → a = F/m → so acceleration depends on
force and
mass
✔ Answer:
force and
mass
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Problem 7: Friction types:
a. is ______________ when an object is not moving.
→
static friction
b. is ______________ when two objects rub against each other.
→
sliding friction (or kinetic friction)
i. ______________ friction a special type of sliding friction when the object slides through a liquid or gas
→
fluid friction
c. is ______________ when the object rolls over another.
→
rolling friction
✔ Answers:
a.
static friction
b.
sliding friction
i.
fluid
c.
rolling friction
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Final Answer:
1. 3000 N
2. 3.57 m/s²
3. 600 N
4. 80 kg
5. unbalanced, acceleration, force
6. force, mass
7. a. static friction; b. sliding friction; i. fluid; c. rolling friction
Parent Tip: Review the logic above to help your child master the concept of newton s 2nd law of motion worksheet.
