# Two Midterm Questions: Velocity of Falling Ball and Acceleration of Braking Car

• Whatup202
In summary, the first problem statement is ambiguous and requires more information to accurately solve. The second problem requires calculating the time and distance for the car to come to a stop, using the given equations and the value of acceleration, and then finding the appropriate acceleration value to ensure the car stops within 112m. It is important to show problem solving attempts in order to receive feedback on methods and address any doubts or errors.
Whatup202
Member warned to post individual problemss in separate threads and to show a solution attempt.

## Homework Statement

The first-
A ball falls off an edge 1m high and lands 0.9m away. What is the velocity of the ball as it falls off the edge, and what is the velocity of the ball as it hits the ground?

The second-
A man is driving at a constant speed of 20m/s. He sees a deer 112m away and breaks to a stop on its position. His reaction time is 0.5s. What is the car's acceleration as the man brakes? How long does it take him to reach the position?

If you could answer any part of either problem I would very much appreciate it.

## Homework Equations

(Not all may be needed.)
Vf=Vi+(a)(t)
Xf=Xi+(Vi)(t)+(1/2)(a)(t^2)
Yf=Yi+(Vi)(t)+(1/2)(a)(t^2)
Vf^2=Vi^2+(2)(a)(Xf-Xi)
Vf^2=Vi^2+(2)(a)(Yf-Yi)

## The Attempt at a Solution

Answers to the first- 1.99m/s and -4.43m/s

Answers to the second- -1.79m/s^2 and 10.67s ( maybe 11.17s)

Last edited:
Also, 'break' and 'brake' are two different things.

Why are you not showing what you have tried? The concept should be fairly simple- knowing the height, you can calculate the time to fall under the influence of gravity. Knowing the time and horizontal distance move, find the horizontal component of velocity.

For the second problem, assuming acceleration "a" use one of your given equations to find the time to speed 0 and the distance traveled in that time in terms of "a". Then find the value of a so that is no more than 112 m.

SteamKing said:
Also, 'break' and 'brake' are two different things.
Lol, I had to post this in between classes and was kind of burned out by the midterm.

HallsofIvy said:
Why are you not showing what you have tried? The concept should be fairly simple- knowing the height, you can calculate the time to fall under the influence of gravity. Knowing the time and horizontal distance move, find the horizontal component of velocity.

For the second problem, assuming acceleration "a" use one of your given equations to find the time to speed 0 and the distance traveled in that time in terms of "a". Then find the value of a so that is no more than 112 m.
I was hoping someone could fact check the answers. Being that I'm a beginner to the subject, I'm not sure my solving is correct.

The first problem statement is ambiguous. If an object simply falls off an edge it should fall straight down with no horizontal displacement. If it has some initial velocity then the details must be given: what is the initial trajectory? Is it moving strictly horizontally before leaving the edge, or is it launched in some other direction?

Please quote the original problem statement precisely.

You should show your problem solving attempts so that you can receive feedback on your methods, not just your results. Confirming or denying a particular numerical result alone is not diagnostic; a simple error in calculation could render an otherwise flawless analysis incorrect. The answer "That is wrong" doesn't really give you a clue as to what actually went wrong, and "That is correct" doesn't address the reason why you had a doubt in the first place.

## 1. What is the purpose of a midterm exam?

The purpose of a midterm exam is to assess a student's understanding of the material covered in the first half of a course. It allows the instructor to gauge the student's progress and identify any areas that may require further review or improvement.

## 2. How should I prepare for a midterm exam?

The best way to prepare for a midterm exam is to review your class notes, textbook readings, and any assignments or quizzes from the first half of the course. It can also be helpful to create study guides or practice quizzes to test your knowledge and identify any areas that may need extra attention.

## 3. Are midterm exams more difficult than regular exams?

This can vary depending on the course and instructor, but generally midterm exams cover material from a shorter period of time and may be less comprehensive than a final exam. However, they can still be challenging and should be taken seriously in order to achieve a good grade.

## 4. Can I use notes or textbooks during a midterm exam?

This is ultimately up to the instructor, so it's important to clarify with them beforehand. Some instructors may allow the use of notes or textbooks, while others may require students to rely on their own knowledge and understanding of the material.

## 5. What happens if I miss a midterm exam?

If you have a valid reason for missing a midterm exam, such as illness or a family emergency, it's important to communicate with your instructor as soon as possible. They may offer a makeup exam or alternative assignment, but it ultimately depends on their policies and the specific circumstances of your absence.

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