To understand just how gravity and skateboarding go together, a look at what goes in some skateboard tricks and skills is an important part of understanding how everything works.
So how does gravity affect skateboarding? Understanding the physics involved in skateboarding is particularly useful to skateboarders when performing their jumps and tricks. It will allow them to identify the major principles that will enable them to properly execute particular moves, which will prove beneficial from a performance perspective.
In addition to the understanding gained, using experience that has been garnered over time through hours from a lot of practice, a look at some of the theories behind the jumps and tricks can provide a clearer understanding of the various mechanics involved. This is most especially useful for people who are still beginner skateboarders.
A book like this one on how to not kill yourself skateboarding will give you a lot more examples of how gravity affects skateboarding
The Physics Behind The Popular Hippie Jump
For this trick, skateboarders often ride along a flat area at a particular velocity (Vh). He will then jump up without putting any force on top of the skateboard. This will allow him to fly in the air with similar horizontal speed as that of the board (which is also drifting at Vh). This ensures that the board stays directly under his feet and he can then land on it.
For this particular trick, the skateboarder has to propel himself by vertically pressing down using his feet. If he presses down on the skateboard using the force of a horizontal nature, that same board will shoot up behind him or in his front. After the skateboarder has jumped off the skateboard, gravity will come into play and he will then follow an arc as he will fly in the air before he then proceeds to land on it again.
The physics involved on this particular skill can be understood by projectile motion – this is where just the vertical part of its velocity changes. This is because gravity solely acts in a vertical direction. Since there’s zero force of gravity that acts on the skateboarder in any horizontal way, the horizontal component regarding his velocity will not change in the slightest (without the issue of air resistance).
A friction force that plays a part on the skateboard when it rolls (as a result of it touching the floor) is minimal and will not slow down the board appreciably. As a result of this, its velocity is almost similar to that of the horizontal speed of the skateboarder. This will then allow the skateboarder to land on the skateboard again.
The Physics Behind The Ollie
This skateboarding trick is a basic one. It is regularly used as a springboard for other tricks that are more complicated. The start of this trick involves two actions that occur at almost simultaneous times. The first one involves the skateboarder jumping off and onto the skateboard.
This is followed by him pressing down instantly on the back part of the skateboard – resulting in it rebounding off the floor and bouncing back. The skateboarder then guides the skateboard with his legs as it makes its way in the air, thereby giving him a chance to land on it when coming back to the ground.
In the first stage, the skateboarder is supposed to be crouched and preparing to jump off the skateboard. His right foot is placed on the tail of the skateboard and his left foot is close to the middle of the board. All forces on the board at this stage are at zero since it is stationary (with zero acceleration).
In the second stage, the skateboarder pushes himself upwards by making his legs straight and then raising up his hands. As that happens, he will push down using his right leg harder than his left foot. This will cause the board to tilt and strike the ground with its tail.
When its tail proceeds to strike the floor, an impulse force is created with the floor. This will propel the board upwards and will also cause it to rotate clockwise. The skateboarder will then slide his left foot along the board to the left side and tilt it, which will allow him to grasp the rough surface of the skateboard using his shoe’s edge.
This will enable him to guide the board during the remaining part of its motion. The force used on the skateboard by the left foot is divided into two different components. One of these components is the force that drags the skateboard along.
In the third stage, his right foot will lose contact with the skateboard. He will then guide the board with his left foot and drag the board upwards and even higher.
In the fourth stage, the skateboarder will then bring the skateboard into a horizontal level by pressing down his left leg while lifting up his right leg, so that it doesn’t accidentally come in contact with the board’s rising tail. He will make contact with the skateboard with both feet and will now be able to squarely land on the board.
It should be noted that the Ollie can as well be done as the skateboarder is rolling at a constant speed on the ground. In this scenario, the physics of the Ollie – already described using the four above stages – will remain the same.
Physics of Skateboarding – The Frontside 180
The physics of this trick is associated with the conservation of angular momentum.
For this trick, the skateboarder rotates his board to 180 degrees while in the air so that at the point of landing, he’ll be facing the opposite direction. He will be able to do this even though his initial momentum is at zero, which means he isn’t initially rotating.
As the skateboarder becomes airborne, the sole force that will act on him is gravity, which acts through the hub of the mass of the system. Due to this, the gravity force will not be able to exert a torque on the system. So, in its entirety, the system will not be able to rotate.
What is the physics behind this and how does the skateboarder manage to rotate the board up to 180 degrees by the time he reaches the ground? He’s able to do this by rotating his lower body and upper body in different directions. With this, he can be able to land with the skateboard facing the opposite direction, while also conforming to the physical requirements that state that the angular momentum remains zero.
The skateboarder will put his upper body in a clockwise rotation, which will result in his upper body being in angular momentum. At that same time, he will give the skateboard and his lower body a counterclockwise rotation, which will result in his lower body and the skateboard being in angular momentum.
Once the skateboarder lands on the ground, it is simply a case of rotating the upper body to face the wall. He can be able to execute this due to the fact that after he lands, he can implement a torque towards the floor, which will then allow his body to be able to rotate so he faces a position that is entirely opposite to where he was facing before.
Physics of Skateboarding – Pumping on a Half-Pipe
This particular tool is used by skateboarders to increase their takeoff speed when they leave the pipe. This will enable them to reach greater heights and also help them perform more tricks while they are airborne.
With this, the skateboarder is able to improve his speed without needing to push off the ground propelling against the force of gravity. What this means is that his feet don’t even need to leave the board. It’s why you have to ask these questions: What physics takes place here and how does the skateboarder improve his speed without needing to push off the ground?
To increase speed, the skateboarder bends down in the straight part of the halfpipe. When he then comes to the curved section of the halfpipe, he will lift up his arms and body, which will then result in him exiting the pipe at an increased speed. The fundamental skateboarding physics behind this can be grasped by applying the principle of angular momentum and impulse.
By constantly pumping his body (he does this by crouching and lifting his body in the curved part of the half-pipe), the skateboarder will be able to increase his speed which will eventually allow sufficient enough height to be attained so as to be able to perform a handful of mid-air tricks.
An intuitive or non-mathematical narration of the physics occurring here is that pumping gives energy to the system in a similar way that a kid pumping on a swing increases energy and also results in him being able to swing higher. Therefore, the physics involved in pumping on a halfpipe is very similar to that of pumping on a swing.
As the skateboarder lifts his body and arms, he will be able to feel some resistance as a result of the force of centripetal acceleration that tends to push his body from the centre of rotation. This resistance actually proves that work is being accomplished, and ultimately, energy is being pumped into the system.