Stationary Bikes

When my mother was using her stationary bike today, it suddenly reminded me of a physics concept. As she keeps on cycling for any amount of time, her "distance" on the bike may say some funky number, like eleven miles, but she hasn't traveled anywhere. Even if she is exercising, her displacement will stay zero because she is not moving. Because her displacement is zero, her velocity will also be zero.

No matter how fast she pedals, no matter what her speed is, she will always stay at the displacement zero and her velocity will stay as zero. For example, the bike, which has a little screen that tells how far she has "traveled" and how long she has traveled, says that she has pedaled 1 mile in 10 minutes. Her average speed would be 6 miles an hour, but her displacement and velocity are both zero.

Sadly, my mother was hesitant to take a picture, and she hid her face with a newspaper while i snapped the photograph. With or without her face in the picture, she still perfectly demonstrates zero displacement and velocity.

Driving Physics Facts

Today, while I was dropping my friend off at her house, I saw a cop and it gave me a huge epiphany. This made me realize how much driving had to do with Physics.

When driving, people usually go a faster velocity than the speed limit (which is usually around 25 miles per hour around my neighborhood), but whenever they see a cop, they suddenly start to slow down to have the same velocity as the speed limit so that they do not have to worry about getting tickets. In the process of slowing down, the car goes through a negative acceleration.

Another physics fact about driving is that when you see a stop sign, you also have to slow down so that the velocity of the car will reach 0 mph, causing the car to go through negative acceleration.

That's enough Physics facts for today. By the way, I'm sorry about not having the picture of the cop, but I did not have a camera. ☺

(P.S. The cars in the picture are randomly taken close to my house.)