# 2016 AP Physics 1 Free Response #3

TLDRIn this video, Alan from Bothell STEM Coach discusses the 2016 AP Physics 1 Free Response Question 3, involving a cart on a track with evenly spaced bumps. The cart reaches a constant maximum average speed after passing the 40th bump. Alan explains the effects of changing the distance between bumps and the incline angle on the cart's speed, examines a student's hypothesis, and evaluates the correctness of an equation relating mass and speed. He concludes by noting the inaccuracies in the hypothesis and encourages viewers to engage with his content for more math and physics insights.

###### Takeaways

- π The cart accelerates down an inclined track with speed bumps, and its average speed stabilizes after the 40th bump.
- π The velocity graph of the cart shows a pattern of increasing velocity followed by a drop, indicating periodic acceleration.
- π Increasing the distance between bumps allows the cart more time to accelerate, leading to a higher maximum speed.
- π Changing the angle of the incline affects the maximum speed, with a steeper angle resulting in greater acceleration due to gravity.
- π A student's intuitive equation for maximum average speed suggests a linear relationship with mass, but it requires verification.
- π Data from experiments indicate a linear trend between the cart's mass and its average speed, but the y-intercept's value raises concerns.
- π€ The provided equation's dependence on distance (D) is questioned, as increasing D should theoretically increase the average speed.
- π The student's plotted data show inconsistencies with the expected zero-intercept in the linear relationship.
- π‘ The discussion includes concepts of gravitational force components, energy, and acceleration in explaining the cart's behavior.
- π₯ The video encourages viewers to engage with the content, subscribe, and seek homework help on platforms like Twitch and Discord.

###### Q & A

### What is the main topic of the video?

-The video is about solving a free response question from the 2016 AP Physics 1 exam, specifically question number three.

### What is the initial setup described in the question?

-The setup involves a long track inclined at an angle theta with small speed bumps evenly spaced distance D apart. A cart of mass M is released from the top of the track.

### What observation does the student make after the cart reaches the fortieth bump?

-The student notices that the cart's average speed between successive bumps no longer increases and reaches a maximum value, V average.

### What graph is the student asked to sketch?

-The student is asked to sketch a graph of the cart's velocity V as a function of time from the moment it reaches bump 41.

### How does the velocity graph look after the cart reaches bump 41?

-The velocity graph shows a pattern of increasing velocity due to acceleration and then a drop, repeating this pattern with straight lines, indicating constant acceleration.

### How does increasing the distance between bumps affect the cart's maximum speed?

-Increasing the distance between bumps allows the cart more time to accelerate between each bump, resulting in a greater maximum speed.

### What effect does tilting the track to a greater ramp angle have on the cart's maximum speed?

-Tilting the track to a greater ramp angle increases the gravitational force component along the track, leading to greater acceleration and a higher maximum speed.

### What is the student asked to consider when deriving an equation for V average?

-The student is asked to derive an equation that is intuitively expected to be true and then check if it makes physical sense.

### What kind of relationship does the student's plotted data show between mass and average speed?

-The plotted data shows a linear relationship between the mass of the cart and its average speed.

### Does the equation make physical sense according to the other student?

-The other student suggests that the equation might be incorrect for reasons other than what the data shows. The data suggests a linear relationship, but the dependency on distance D seems incorrect.

###### Outlines

##### π Introduction to Physics Problem 3

Alan from Bothell STEM Coach introduces the AP Physics 2016 Physics 1 free response question number 3. He describes a long track with an incline and speed bumps, where a cart of mass M is released from the top. After reaching the 40th bump, the cart's average speed between bumps no longer increases. Alan sketches a graph of the cart's velocity as a function of time and explains the concept of constant acceleration due to gravity.

##### π Analyzing Speed and Bump Distance

Alan discusses how increasing the distance between bumps affects the maximum speed of the cart, suggesting it would be greater due to more time to accelerate. He then examines the effect of increasing the ramp angle, concluding that a steeper angle would result in a greater maximum speed due to increased gravitational force. Alan critiques a student's equation for the cart's maximum average speed and performs a linear relationship analysis with mass.

##### π§ͺ Examining Physical Sense of Equation

Alan evaluates whether the student's equation makes physical sense by considering the effects of changing bump spacing and angle. He argues that as the distance between bumps increases, so should the cart's average speed, contrary to the student's data. Alan admits to a mistake in interpreting the linear relationship and points out that the y-intercept should be zero. He concludes that the distance dependency in the student's equation is incorrect.

##### π Final Thoughts and Homework Help Offer

Alan reviews the scoring guidelines, confirming the key points about acceleration and gravitational force. He reflects on his mistake regarding the linear relationship and corrects it. Finally, Alan invites viewers to his Twitch or Discord for free homework help, encouraging them to engage with him for further learning and support in math and physics.

###### Mindmap

###### Keywords

##### π‘AP Physics

##### π‘Free response questions

##### π‘Incline angle

##### π‘Average speed

##### π‘Constant acceleration

##### π‘Mass

##### π‘Velocity

##### π‘Gravitational force

##### π‘Motion detector

##### π‘Data analysis

###### Highlights

Introduction to AP Physics 2016 Physics 1 free response questions by Alan.

Explanation of the scenario involving a cart of mass M released from rest on a track with speed bumps.

Student observes that the cart's average speed between bumps reaches a maximum after the fortieth bump.

Sketching a graph of the cart's velocity as a function of time starting from the 41st bump.

Explanation of the cart's acceleration and deceleration due to gravity and constant force.

Impact of increasing the distance between bumps on the cart's maximum speed.

Effect of increasing the ramp angle theta on the cart's maximum speed.

Explanation of the force components mg cosine theta and M sine theta in relation to the ramp angle.

Discussion on deriving an equation for the cart's maximum average speed.

Student tests the derived equation using a motion detector and varying the mass M of the cart.

Observation of a linear relationship between the mass of the cart and its average speed.

Consideration of whether the derived equation makes physical sense.

Explanation of how increasing the distance between bumps should affect the cart's average speed.

Evaluation of the linear relationship in the student's data and the discrepancy in the y-intercept.

Conclusion and reminder of free homework help available on Twitch and Discord.

###### Transcripts

5.0 / 5 (0 votes)

Thanks for rating: