As you are walking, you foot gets caught on an uneven piece of sidewalk and you trip and fall. Which of the following explains what is happening using Newton's Laws?

Question

a
The sidewalk pushed you, causing a rapid force that made you fall
b
The sidewalk provided a force to stop your foot, but the top of your body was still moving which is what causes you to tip over
c
Your foot hit the sidewalk and provided a force on it, so the sidewalk will provide another force back on your foot, equal in magnitude but opposite in direct
d
Your foot pushes the sidewalk with such force that it causes the next piece of sidewalk to be uprooted, which makes your next step miss your footing
Question 30
A block with a mass of 55 kg is pulled with a force of 220 N. Assuming a frictionless surface, what will be the acceleration of the block?

a
9.8 m/s2

b
22 m/s2

c
0.25 m/s2

d
4.0 m/s2

Answer 1

For the first question about the trip and fall scenario, the best explanation using Newton's Laws is:

b. The sidewalk provided a force to stop your foot, but the top of your body was still moving which is what causes you to tip over.

This option aligns with Newton's first law of motion, which states that an object in motion will remain in motion unless acted upon by an external force. When your foot hits the uneven sidewalk and stops, your upper body continues to move forward due to inertia, leading to a tipping motion and ultimately a fall.

For the second question regarding the block's acceleration:

You can use Newton's second law of motion, which states that \( F = ma \) (force equals mass times acceleration). Rearranging this gives us:

\[ a = \frac{F}{m} \]

Inserting the values from the problem:

• \( F = 220 , \text{N} \)
• \( m = 55 , \text{kg} \)

Calculating the acceleration:

\[ a = \frac{220 , \text{N}}{55 , \text{kg}} = 4 , \text{m/s}^2 \]

Thus, the correct answer is:

d. 4.0 m/s²