That was the question a physics teacher asked his students. Dr. Scott Lee, currently teaches at the University of Toledo, USA. He thinks that education is about creating excitement for students.
So, instead of giving dry problems that make introductory physics class sleepy and boring, Dr. Lee posed a different question. He asked his students to calculate:
Can Usain Bolt, an eight-time Olympic champion Jamaican, run away from a Dilophosaurus in his 100m range?
“A big problem in physics education today is how to get students interested in the course material.”Dr. Lee said. “These dinosaur math problems, for example, really captivated students and kept them interested.”
In a new article in the journal Physics Pedagogy, Dr. Lee describes his experience in the class, gives the solution to the problem, and encourages other physics teachers to change the way they teach. their tradition.
If you are also interested in this way of teaching physics, let’s find out.
Let’s talk about Usain Bolt . first
Referring to the fastest runner on the planet, people will mention Usain Bolt. The Jamaican made history for the first time at the 2008 Beijing Olympics. That same year, he broke his own world record in the men’s 100-meter final to take gold with a time of 9, 69 seconds.
Unsain Bolt alone dominated the track, even outpacing the second runner who finished in 9.89 seconds. Bolt even slowed down to celebrate in front of the line “finish“.
The Jamaican athlete seems to want to save another record-breaking time. Because according to his coach, if he hadn’t slowed down, Bolt would have finished in 9.52 seconds.
Usain Bolt’s deceleration at the finish line even attracted a group of physicists at the University of Oslo who sat down to calculate how much faster he would reach the finish line with no reduction in acceleration? Their results are relatively close: 9.55 seconds.
A year later at the 2009 World Championships in Berlin, Bolt proved it. He continued to break his own old record at 9.58 seconds.
According to a 2013 study by physicists from the National University of Automation of Mexico, Usain Bolt can achieve an acceleration of 9.5 m/s2 at the starting line and generates 2.6 kilowatts (3.5 hp) in less than 1 second.
He has a height of 1m95, taller than many other sprinters. That means Bolt’s stride is also longer and he can take fewer runs to finish his distance.
However, in the opposite direction, Bolt also encounters greater air resistance. Calculations show that he uses only 8% of his energy to run, while up to 92% of his energy is to overcome aerodynamic drag.
But if he runs smoothly, Mexican scientists calculate that Bolt will benefit slightly. Specifically, if the 2009 race takes place in the quiet, his achievement will be 0.1 seconds short, stopping at 9.68 seconds/100 meters.
Conversely, if there is a whirlwind and Bolt catches it, he can finish the race with a record time of 9.46 seconds/100 meters.
What about the dinosaurs?
Scientists have long been intrigued by the top speed of dinosaurs, especially the Tyrannosaurus rex. In 2002, a team of researchers built a mathematical model to measure T-rex leg muscle mass.
They think according to this model, the T-rex can only run at a maximum speed of 40 km / h. But there are also other studies, based on many parameters such as aerodynamics, structure and tail movement, including the footprints left by T-rex, which show that this dinosaur mainly walked only at 4 speed ,6 km/h.
If the T-rex runs or walks briskly, it also won’t exceed the top speed of about 18 km/h. On the one hand, calculations show that running causes the T-rex to lose energy very quickly. On the other hand, scientists think that it may break a leg bone if it runs above 18 km / h, because of its large body mass.
At this speed, T-rex will not be able to catch up with Usain Bolt, with a maximum speed of up to 43 km / h that he achieved on the track. That’s the main reason why Dr. Lee chose Dilophosaurus, the smaller dinosaur, to represent the Jamaican athlete.
Dilophosaurus is an early Jurassic dinosaur. It is about 3 meters tall, about 7 meters long from head to tail and weighs about 400 kg. Some scientists predict that Dilophosaurus could run at a maximum speed of 10.5 m / s. This is the same speed as Usain Bolt when he set the world record in 2009 in Germany.
However, the problem that the students in Dr. Lee’s class identified was that they had to compare Bolt’s acceleration with that of the dinosaur in this race. According to Newton’s second law, acceleration can be calculated as the derivative of velocity with respect to time.
The students calculated the horizontal acceleration of Usain Bolt to be 9.91 m/s2. While dinosaurs with more mass at the starting line will only achieve an acceleration of 4.19 m/s2.
With the advantage in mass, Bolt will therefore easily outrun the Dilophosaurus in the first 2-4 seconds of the race. “In fact, Usain Bolt’s average speed in the 100-meter race is close to that of Dilophosaurus’ top speed, which means that Usain Bolt will win the entire competition.“, Dr. Lee wrote.
His students then calculated several other parameters and tabulated displacements for both Usain Bolt and the dinosaur Dilophosaurus, tables showing velocities and accelerations over time.
Dr. Lee said that through this exercise, his students have applied many formulas, from instantaneous velocity, acceleration, average velocity to arithmetic methods to draw graphs.
“They also approached the question with great enthusiasm“, Dr. Lee wrote.My students are almost immersed in the problem and are very enthusiastic about working to find the answer.” This was clearly a successful teaching experience that he wanted to share with everyone.
Refer to Arstechnica