Unit 8a Forces and Motion Study Guide

Question

TIP: You MAY use this study guide and the periodic table on your test. Do not use Brainly or any other answer website to find answers. This is a direct violation of the Honor Code.

Part A
John walks to the pizza place for lunch. He walks 2 km north then 1 km east. To get home he walks 2 km south and 1 km west. What distance did he travel? Answer:
What is his displacement? Answer:
How is velocity calculated? Answer:
How is acceleration measured? Answer:

Part B
On a position–time graph, what does the value of the slope indicate about the object? Answer:
What is the term for how far an object has traveled from its original location?
Answer:

Use the following graph to answer the questions.

In what time range is the object stopped? Answer:

What is the position of the object at 3 seconds? Answer:

What does a velocity time graph show? Answer:

During what time period does the object have a constant velocity (no acceleration)? Answer:
What are three ways to cause an acceleration? Answer:
During what time period does the object have acceleration? Answer: Deceleration? Answer:

Part C
Identify which of Newton’s Three Laws of Motion for given scenarios.
An object flying through space will continue moving until gravity pulls it down to a planet. Answer:
A car traveling on a road. The tires push forward on the road but the road pushes on the tires. Answer:
Two people sitting in rolling chairs push off of each other and move in opposite directions. The smaller person accelerates faster than the larger. Based on Newton’s Second Law of Motion, how would an increase in mass affect an object’s acceleration? Answer:
Is force a scalar or vector? Answer:
How is a scalar quantity different from a vector quantity? Answer:
Essay Questions:
Directions: Below are essay questions you may encounter on your test. Please prepare your answers now and use this sheet to help you write your answers on the test. DO NOT COPY any answers from Brainly or any other outside sources. That is a direct violation of the Honor Code. I will be looking for those specifically. Your answer must come from information provided in the lessons.
An elevator in a hotel starts at ground level. It rapidly moves up to the third floor, where it stops to unload passengers. The elevator then descends to the basement at a slower speed than before.
In 1–2 sentences, identify whether or not the graph correctly represents the story. Explain your answer.
Answer:

A student holds a water balloon outside of an open window and lets go. The window is 10 meters above the ground, and the balloon is falling under the acceleration of gravity, which is 9.8 m/s2. There are two equations that can be used to describe its motion over time:
Would the balloon hit the ground before or after 1.0 s of falling? Which equation did you use to decide, and what comparison did you make to determine that it would or would not hit the ground by then? Use 3–5 sentences to explain your reasoning and show all work including: givens, unknowns, equation, substitutions and final answer. Answer:
Many competitive swimmers practice in loose-fitting, baggy swimsuits called drag suits. In 1–2 sentences, explain how, in terms of the forces acting on a swimmer, wearing a drag suit differs from wearing a tight-fitting racing suit, and why practicing in a drag suit can make a swimmer stronger. Answer:

Answer 1

Unit 8a Forces and Motion Study Guide

Part A

John's Journey:

1. Total Distance Traveled:

   • Walking 2 km north, then 1 km east, then 2 km south, and finally 1 km west.
   • Total Distance = 2 km + 1 km + 2 km + 1 km = 6 km.

2. Displacement:

   • John ends up back at his starting point after the journey, so his displacement is 0 km.

3. Velocity Calculation:

   • Velocity is calculated using the formula: Velocity = Displacement / Time.

4. Acceleration Measurement:

   • Acceleration is measured in units of meters per second squared (m/s²).

Part B

1. Slope on a Position-Time Graph:

   • The value of the slope indicates the velocity of the object; a steeper slope means a higher velocity.

2. Term for Distance from Original Location:

   • The term is displacement.

3. Object Stopped:

   • The object is stopped when the position-time graph is flat (slope of 0).

4. Position at 3 Seconds:

   • This answer would depend on the specific graph provided; typically, you would identify the position on the graph at the 3-second mark.

5. Velocity-Time Graph:

   • A velocity-time graph shows the change in velocity over time.

6. Constant Velocity Period:

   • The object has a constant velocity when the graph shows a horizontal line.

7. Ways to Cause Acceleration:

   • Three ways to cause acceleration are:
     • Changing speed (speeding up or slowing down).
     • Changing direction of motion.
     • Changing the shape of the path (e.g., circular motion).

8. Acceleration Period:

   • The object has acceleration when the velocity-time graph has a slope (it is not horizontal).

9. Deceleration Period:

   • Deceleration occurs when the velocity is decreasing, which can be represented by a downward slope on a velocity-time graph.

Part C

1. Newton’s Laws Identification:

   • First Law: An object flying through space will continue moving until gravity pulls it down to a planet.
   • Third Law: A car traveling on a road. The tires push forward on the road but the road pushes on the tires.
   • Second Law: Two people sitting in rolling chairs push off of each other and move in opposite directions. The smaller person accelerates faster than the larger. An increase in mass would decrease acceleration if the force is constant.

2. Force as Scalar or Vector:

   • Force is a vector quantity.

3. Scalar vs. Vector Quantity:

   • A scalar quantity has only magnitude (e.g., mass, temperature), while a vector quantity has both magnitude and direction (e.g., force, velocity).

Essay Questions

1. Elevator Graph Analysis:

   • The graph correctly represents the story; as the elevator moves up rapidly and then descends at a slower speed, this would be depicted by a steep incline followed by a gentler decline on the graph.

2. Water Balloon Drop:

   • Given:
     • Height (h) = 10 m
     • Acceleration (g) = 9.8 m/s²
     • Unknown: Time (t) when the balloon hits the ground.
   • Using the equation \( h = \frac{1}{2} g t^2 \):
   • \( 10 = \frac{1}{2} (9.8) t^2 \)
   • \( 10 = 4.9 t^2 \)
   • \( t^2 = \frac{10}{4.9} \)
   • \( t^2 \approx 2.04 \)
   • \( t \approx \sqrt{2.04} \approx 1.43 \) seconds.
   • Since 1.43 seconds is greater than 1.0 seconds, the balloon would hit the ground after 1.0 seconds.

3. Drag Suits vs. Racing Suits:

   • Wearing a drag suit creates more drag through the water, increasing resistance, which requires more force and effort from the swimmer. Practicing in a drag suit can improve strength and technique by forcing the swimmer to work harder against the increased resistance compared to a tight-fitting racing suit, which minimizes drag.