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Question 28

Look at Zeke.

He’s riding his skateboard down a ramp. Assume that his acceleration is 0.8 m/s2. How much force does it take for him to accelerate at this rate? Zeke has a mass of 50 kg.

a
62.5 N
b
50 N
c
40 kg
d
40 N
Question 29
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?

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

1 answer

Let's solve each question step-by-step:

Question 28: To find the force that causes Zeke to accelerate, we can use Newton's second law of motion, which states that \( F = ma \), where:

  • \( F \) is the force,
  • \( m \) is the mass,
  • \( a \) is the acceleration.

Given:

  • Mass (\( m \)) = 50 kg
  • Acceleration (\( a \)) = 0.8 m/s²

Calculating the force: \[ F = ma = 50 , \text{kg} \times 0.8 , \text{m/s}^2 = 40 , \text{N} \]

Answer for Question 28: d) 40 N

Question 29: In this scenario, you're tripping and falling. We can analyze this using Newton's laws.

  • Option a: Incorrect, the sidewalk does not push; your foot is stopped.
  • Option b: Correct. When your foot gets caught, it stops moving, but the top half of your body continues to move forward, causing you to tip over.
  • Option c: While it does describe action-reaction forces, it doesn't explain why you fell.
  • Option d: Incorrect. It misrepresents the interaction between your foot and the sidewalk.

Answer for Question 29: 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.

Question 30: Again, using Newton's second law, \( a = \frac{F}{m} \).

Given:

  • Force (\( F \)) = 220 N
  • Mass (\( m \)) = 55 kg

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

Answer for Question 30: d) 4.0 m/s²

Final Answers:

  • 28: d) 40 N
  • 29: 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.
  • 30: d) 4.0 m/s²