# Velocity needed to launch a car

• NEUhusky
In summary, the conversation discusses a homework assignment in a physics-related class where the task is to find an action movie clip that portrays something impossible. The chosen clip is from Transporter 2 and the group is trying to figure out the velocity needed for a car to launch off a roof and land 18 meters away. The conversation includes calculations and assumptions, and ultimately concludes that the movie effects may be deceiving and the force needed to break through a concrete barrier will also need to be considered.
NEUhusky

## Homework Statement

Hi all, this is my first post here because I am having an issue with an assignment in my General Engineering class (physics related). The assignment is to find an action movie clip that portrays something to be real but is, in reality, not possible. My group and I decided on this clip from Transporter 2:

Now, we have three problems in the scene that we need to figure out. We are going to work backwards and start with the velocity a car would need to launch itself off a roof and land on something (we estimated) 18 meters across and 18 meters below. We figured the car dropped about six stories, 10 feet per story, which is approximately 18 meters. We also did some research and found a 4 lane road plus sidewalks would be about 18 meters across. We're allowed to make assumptions as obviously some things cannot be known by just watching a movie.

## Homework Equations

I've done multiple kinematics equations but all of the answers seem to be too low. I guess my main question is, how can the mass of the car not be taken into consideration when trying to estimate to the velocity needed for a 4000 pound car to clear 18 meters?

## The Attempt at a Solution

There are two unknowns. The initial velocity of the car, and the time it takes for the car to clear 18 meters. My attempt at solving:

-18 = Viy + (.5)(-9.8)(t2)

=

-18 = -4.9t2

3.67 = t2

t = 1.91 s

Now, knowing the time, I solve for velocity:

18 = Vi(1.91)+(.5)(0)(1.91)

=

18/1.91 = Vi

Vi = 9.42 m/s

9.42 m/s is around 21mph. I'm sitting here looking at my 6 story apartment and trying to visualize a 4000 pound car driving at that slow of pace and landing 18 meters from where it started. What am I missing here? Thanks in advance!(the force needed to break through a concrete barrier will be solved later)

Last edited by a moderator:
That calc looks good...neglecting air resistance, which should not be too much of a factor in that short time and distance. 20 mph isn't that slow...

True. Thanks for the reply. I guess the movie effects are just playing tricks on my eye. The kicker will have to be the force required to break a concrete barrier and sustain the velocity needed to make the jump.

## 1. What is the formula for calculating the velocity needed to launch a car?

The formula for calculating velocity needed to launch a car is: velocity = square root of (2 x gravity x distance), where gravity is usually taken as 9.8 m/s².

## 2. How does the weight of the car affect the velocity needed for launch?

The weight of the car affects the velocity needed for launch because a heavier car will require more force to overcome its inertia and achieve the necessary acceleration. This means a heavier car will require a higher velocity for launch compared to a lighter car.

## 3. Can the velocity needed for launch be increased by adding more power to the car?

Yes, adding more power to the car can increase the velocity needed for launch. This is because more power means more force, which can result in a higher acceleration and ultimately a higher velocity.

## 4. Is there a minimum velocity needed for a successful car launch?

Yes, there is a minimum velocity needed for a successful car launch. The minimum velocity needed will depend on factors such as the weight of the car, the distance to be covered, and the surface conditions. However, a general rule of thumb is that a velocity of at least 20 m/s is needed for a successful car launch.

## 5. How does the angle of the launch ramp affect the velocity needed for a car launch?

The angle of the launch ramp can affect the velocity needed for a car launch in two ways. A steeper angle will result in a higher initial acceleration, which means a lower velocity is needed for launch. However, a steeper angle also means a higher vertical component of the launch velocity, which can result in a shorter horizontal distance covered. So, the angle of the launch ramp must be carefully chosen to balance these factors and achieve the desired launch velocity and distance.

• Introductory Physics Homework Help
Replies
8
Views
3K
• Introductory Physics Homework Help
Replies
10
Views
3K
• Introductory Physics Homework Help
Replies
1
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
3K
• Engineering and Comp Sci Homework Help
Replies
1
Views
696
• Introductory Physics Homework Help
Replies
6
Views
1K
• Introductory Physics Homework Help
Replies
5
Views
977
• Introductory Physics Homework Help
Replies
15
Views
2K
• Introductory Physics Homework Help
Replies
2
Views
8K
• Introductory Physics Homework Help
Replies
16
Views
1K