# Attempt to jump across a river on a motorcycle

• Chan M
In summary, a physics professor attempted a daredevil stunt of jumping across a river on a motorcycle. The takeoff ramp was inclined at 53 degrees, the river was 40 m wide, and the far bank was 15 m lower than the top of the ramp. To make it to the edge of the far bank, the professor needed to have a speed of 17.8 m/s at the top of the ramp. However, if his speed was only half of this value, the professor would have landed either in the river or on the cliff, which would need to be calculated using the given equations and a drawing.
Chan M

## Homework Statement

A physics professor did daredevil stunts in his spare time. His last stunt was an attempt to jump across a river on a motorcycle. The takeoff ramp was inclined at 53 degrees, the river was 40 m. wide and the far bank was 15 m lower than the top of the ramp. The river itself was 100 m. below the ramp. You can ignore air resistance.What should his speed have been at the top of the ramp to have just made it to the edge of the far bank? If his speed was only half the value found in (a), where did he land?

Xo = 0m
X = 40m
Ax = 0 m/s^2

Yo = 15m
Y= 0m
Ay = -9.8 m/s^2

2. Homework Equations

X = Xo + VoT + 0.5(Ax)T

Voy = Vo*sin(53)
Vox = Vo*cos(53)

X = Vox*T (since acceleration in the x-direction is zero)

3. The Attempt at a Solution

0 = 15 + VoyT - 4.9(Ay)T

0 = 15 + Vo * sin(53) * (40 / (Vo * cos(53) ) - 4.9 (40 / Vo * cos(53) )^2

My professor gave me the answer (17.8 m/s) but I still need to know how to solve the problem?

Thanks!

Last edited by a moderator:
Chan M said:

In these problems it helps a lot to make a drawing to guide you.
Remember that in the first question, the landing point is 15m below the point of origin.
But in the second question, the point of contact is in the river, or on the cliff, you don't know that and you must calculate it. (you have inicial velocity)

Be careful with the signs of speeds, and accelerations, and applying the equations should not be too hard.

## 1. What is the success rate of attempting to jump across a river on a motorcycle?

The success rate of this attempt depends on various factors such as the width of the river, the speed and power of the motorcycle, and the skill of the rider. Generally, this type of stunt is considered extremely dangerous and should not be attempted.

## 2. What are the potential risks and dangers of attempting this stunt?

There are numerous risks and dangers associated with attempting this stunt. These include but are not limited to: crashing into the river, getting swept away by strong currents, hitting rocks or debris in the river, and sustaining serious injuries or even death.

## 3. What precautions should be taken before attempting this stunt?

If one still chooses to attempt this stunt, it is crucial to take proper precautions. These may include checking the motorcycle for any mechanical issues, ensuring the rider is wearing appropriate safety gear such as a helmet and protective clothing, and having a team of experienced professionals present to assist in case of an emergency.

## 4. Has anyone successfully completed this stunt before?

While there have been some instances of successful river jumps on a motorcycle, these are rare and often performed by highly skilled professionals with years of experience and specialized equipment. It is not recommended for the average person to attempt this stunt.

## 5. Are there any legal implications for attempting this stunt?

The legality of attempting this stunt varies depending on the location and local laws. In most cases, it is considered dangerous and reckless behavior, and may result in fines or other legal consequences. It is important to research and understand the laws and regulations before attempting such a stunt.

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