Fast and Furious 7, one of my favorite movies to date, contains an abundance of physics defying scenes that could only be possible in Hollywood. Multi million dollar cars jumping skyscrapers and driving out of planes. A man running atop a coach bus as it slides off a cliff. Scenes like this make me ask: Could any of this really happen? This article will showcase my favorite scenes from the movie and by applying the basic principals of physics I hope to uncover whether any of this action could take place in real life.
Perhaps my favorite scene is when Dom’s (Vin Diesel) team decided to load up their cars in a cargo jet and then drive out mid flight, tumbling down to earth on parachutes. Safely landing on a road in the mountains and speeding away. Cars unharmed.
It’s no doubt that cars are extremely heavy and by no means streamlined enough to gently glide down to earth as a typical skydiver does. Therefore there would be a lot of stress on the parachute. The initial opening and throughout the flight. There is no reason why this wouldn’t work because a parachute slows down a mass proportional to the parachute area. This means you could even attach parachutes to the international space station and with a large enough area, have it return to the ground at a reasonable speed. As a more reasonable example, the military drops tanks with parachutes.
So far we know that a parachute would be able to slow a car’s descent to earth however what we don’t know is the size of parachute needed, how fast the car would descend and if it would be able to take the impact of landing on a road and drive away as seen in the movie.
Lets start with the parachute diameter. Could a parachute of this size reasonably fit into the cars they were driving? To calculate this we will need the approximate mass of the car and the area of the parachute. One of the cars dropped was a 2011 Dodge Challenger R/T (1852 kg + 54 kg driver), the classic American muscle car was driven by Letty (Michelle Rodriguez).
When the chute opens the car will speed up towards the ground until the drag force (Fd) on the parachute is equal to the weight (Fg) of the car, including gravity. So Fd = Fg.
Fd is the drag force
⍴ is the density of air = 1.22 kg/m3
Cd is the drag coefficient = 1.5 (domed parachute with circular hole at the top)
A is the area of the chute
v is the velocity through the air (we can set this to the wanted touchdown velocity)
m is the mass of the car = 1906 kg
g is the force of gravity on earth = 9.81 m/s²
We know that the max speed the car will travel when the chute is open is when Fd = Fg.
Finally we can calculate the size of parachute needed. However we are missing one large piece of data. What is a safe velocity that the car can touch down on the road with? We can estimate this **. Without a parachute a car could likely survive a fall from 3 times its height. The Dodge is 1.5 m tall therefore it’s safe landing velocity would be 9.4 m/s. See calculations below.
** You can calculate the true maximum velocity the 2011 Dodge Challenger R/T could touch down with, before its steel (low carbon steel) chassis bends. The typical strength of low carbon steel is around 60000 psi and at the car’s weakest point, its axle has a diameter of only ≈ 2.5 in. When watching the scene it’s noted that the rear wheel of the car is first to touch down this means all of the downward force is exerted on that one point. The typical strength, mass of the car and a few other specifications for higher accuracy can be put into a bending / flexure formula to determine the maximum safe touch down velocity. If someone wants to calculate this leave a comment bellow with your math and I’ll add it in the article!
How scary would this experience be? Before and after the chute opened the cars were in free fall long enough to have reached terminal velocity. Terminal velocity is the fastest speed an object can fall through the air. It occurs when the drag force (Fd) is equal to the force of gravity (Fg), resulting in zero acceleration. This would have been around 200 – 300 mph!
The coolest part about this scene is that it was mostly composed of real footage! Check out the behind the scenes here. I appreciate that the directors of the movie didn’t rely as much on CGI for F&F7 and tried to do as many real shots as possible. This scene was just plane crazy!
I don’t think anyone was expecting to see a Lykan Hypersport jump skyscrapers when they watched Fast and Furious 7 for the first time. There were many car stunts throughout the movie but this one was the most ridiculous of them all. Dom and Brian steal the 3.4 million dollar Lykan HyperSport from a penthouse suite, driving around the floor with naturally no roads to travel on. When an assassin, with a machine gun grenade launcher comes to kill them, Dom decides to jump the expensive sports car from one Abu Dhabi skyscraper to another. Against the odds he makes the jump. Then resizing their brakes don’t work they jumps yet another tower. Of course my first reaction was: Could this actually happen?
Scene starts at 1:47 min.
If the car was able to gain enough speed theoretically it could make the jump, but how fast is fast enough?
The towers mentioned are a huge 5 skyscraper tower complex in Abu Dhabi called the Etihad Towers. The tallest tower being 1002 ft height.
The Lykan HyperSport with two grown adults would have weighed around 1568 kg (1380 car + 102 Dom + 86 kg Brian). Using Google Maps I was able to estimate the distance between the buildings and the width of the buildings. See Figure 2.0. Seeing that the width of Tower 2 was only 133 ft compared to the 200 ft jump that followed I was skeptic of this jump actually taking place in real life. The jump from Tower 3 to Tower 4 looks much more reasonable. For the following calculations lets also assume zero wind resistance and a clear sky.
The first jump from Tower 2 to Tower 3 is about 61 m. We also know that the car ideally has a runway of 200 ft, a mass of 1568 kg. Once it jumped the car seemed to be tilted at an angle of 11 degrees. I calculated the theoretical angle (angle z) below which is close to the 11 degree angle seen in the film. This is within the expected range of error for such a calculation. There are 74 stories in Tower 2 and 54 in Tower 3. Respectively their heights are 305 m and 260 m tall. This results in an average story height of 4.5 m [305/74+(260/54)/2]. The observed falling height was 2 stories therefore we conclude that the car fell roughly 9 meters 4.5*2=9.
Lets start with the y axis when the car undergoes free-fall and uniform acceleration due to gravity.
Falling two stories (9 m) takes about 1.4 seconds.
On the x axis there is no acceleration and the object undergoes constant velocity. Time can be carried over from the y to the x axis.
In order to cover the necessary 61 meters in this time the car would have to be traveling at a speed no slower than 157 km/h (43.6 m/s) as it left Tower 2, a speed certainly achievable by this supercar. Now that we have the speed needed in order to make a successful jump to Tower 3 we need to figure out if this speed be reached, starting from a standstill, in the 40.5 m of “runway” Dom and Brian have. The Lykan Hypersport can do 0 to 96.9 km/h (60 mph, 27 m/s) in just 2.8 seconds.Now that we have calculated acceleration lets put it into a kinematics equation to figure out how much “runway” we need to reach 157 km/h (43.6 m/s), the minimum speed required to make the jump.
In order to successfully make the jump from Tower 2 to Tower 3 a minimum building width of 99 m (325 ft) is required. As seen in Figure 1.0 the building is only 40.5 m (133 ft) wide. Therefore this jump could not have happened in real life! However the jump from Tower 3 to Tower 4 could be more plausible.
This scene is insane! Best part of all it’s not to far from being possible. I like every part of it. The assassin with a grenade launcher who leaves them no choice but to jump buildings and not to mention the beautiful car they are driving.
Fast and Furious 7 is filled with exploding cars and buildings. It’s no surprise explosions in movies are often exaggerated. You’ll notice in films, especially Fast and Furios 7, that things tend to explode with a huge fireball. A simple dive to the ground can save your life and you’ll walk away with no injuries.
The scene in question here is when Dom (Vin Diesel) receives a mysterious package from Tokyo on his doorstep. Standing no more than 20 ft (6.1 m) away he realizes that the package is a bomb, delivered by the assassin out to kill his team. A split second before it explodes he runs than dives on top of his sister Mia (Jordana Brewster) to get her out of harms way. The two are knocked to the ground on the sidewalk by the force of the explosion and the kinetic energy he originally had running and then diving on her. The bomb had enough energy to blow up the house as well. Next door Dom’s brother Brian (Paul Walker) just closed the door to a minivan, where his son was sitting. Brian was thrown against the minivan with a large enough force that his head broke the window. Once the dust settled they all walked away unharmed. Dom, Mia, Brian and his Son. Is this possible?
When I saw this scene I was skeptic because there is no way a bomb, on your doorstep could blow up an entire house leaving you, standing less than 20 ft away unharmed. Even a grenade at that proximity would likely kill you.
There are several ways a bomb can injure you.
Case one: The heat energy and fireball from the observed explosion would either severely burn you or set you on fire.
Case two: The blast waves from the explosion will send out fragments that travel very fast. Debris flying at race car speeds would cause injuries such as penetrating wounds, impalement, broken bones, or even death.
Case three: When a bomb detonates the energy released from the explosion radiates outward in all directions, equally. This creates a sphere of energy that can travel anywhere from 3 to 9 km per second. As this sphere expands, it compresses and accelerates the surrounding air molecules into a supersonic blast wave. Even though this over pressure only exists for a couple milliseconds its enough to seriously injure or kill you. The further you are away from the blast the safer you are as this shock wave decreases exponentially.
Case four: The wave in case two is followed by a second shock wave. As this wave hits your body, crunching your vital organs it forms a perfect seal as it travels past you, taking everything including the surrounding air with it. This creates a near perfect vacuum for a split second. The air that surges back (blast wind) to fill the vacuum is strong enough to hurdle a grown man standing on his feet several meter, even further if he is mid jump, as Dom and Mia were. You’d end up smashing into something such as a concrete sidewalk or minivan at three digit speeds which would likely kill you.
Judging by the structural damage caused to the house, the peak overpressure was probably 3 – 5 psi. See Table 3.0. Its almost certain everyone would have been severely injured and some people would have likely died. Sadly including Brian’s son in the car who would have been injured from shards of glass from the van’s window.
This of course is all theoretical due to the limited information given from the scene. Such as the type of explosive used. If I just saw the explosion and none of the damage it cause I would have guessed it was just a petrol bomb due to how big the fireball was. However another high explosive would have needed to accompany the petrol to cause such damage.
Leaving the physics behind this scene was extremely entertaining and had a happy ending. You could also see the desire for revenge in Dom’s eyes. It was the perfect setup for the rest of the movie showing the assassin would stop at nothing to try and kill them.
Dwayne Johnson and Jason Statham Fight
In Fast and Furious 7 I can’t count how many time glass shatters after someone is thrown into it. Seems like everytime a person falls backwards in a movie they somehow manage to hit something glass.
In F&F7 Luke (Dwayne Johnson) discovers Shaw (Jason Statham) in his office hacking into the computer. In an attempt to escape Shaw tries to kill Luke. The two go at it in a spectacular fight scene that of course manages to shatter six glass sheets!
Lets just assume that the two were throwing each other with enough force that they could break the thick windows in an office building. The shattering of the windows would have likely caused serious injury. Possibly slicing off body parts and causing huge wounds. One small cut can result in an unimaginable amount of blood loss. Could this scene happen in real life with both walking away bloodied as they did in the movie? Probably not.