FOOTBALL INTERCEPTION!

on friday i went to the campbell vs. iolani football game at roosevelt. there i witnessed lots and lots of projectile motions and i took a video of an interception!! what good timing :) okay so the horizontal displacement would be the distance from where the ball was thrown from til where it was caught or intercepted. the free body diagram of the football would include its weight, mg. however, there would be no normal force since the football is not on a surface. its x-acceleration would be 0 m/s squared while its y-acceleration would be -9.8 m/s squared. the end.

HANGING CALENDAR

okayyy so i had to think what to do my blog on...and i thought for quite a while and i decided to write about my hanging calendar. i hope this counts as something relating to physics. the calendar is hanging straight because its mass is balanced. this is due to the physics concept of center of mass. every object has a special point called the center of mass, which if not supported, will fall. center of mass is the average position of the mass distribution. the pin is balancing the calendar. if the pin were towards one end of the calendar, then it would be hanging crookedly. this is why center of mass is important. the end!

SHOPPING CARTS COLLIDING

on saturday, my mom and i went to times supermarket. while i was there, i witnessed physics when a lady pushed a shopping cart into another shopping cart at rest which was in the rack. so then i went to another rack and experimented. when i pushed the shopping cart, its momentum was its mass times its velocity, p=mv. because the shopping carts sticked together, its collision was inelastic. in inelastic collisions, the kinetic energy of the system is not conserved. however, the momentum of the system is always conserved whether it is an elastic or inelastic collision. using the law of conservation of momentum, pi1+pi2=pf1+pf2, we can find the velocity of the second shopping cart. haha at least i think this is what happened when the shopping carts collided.

LIFTING DOGS

today i had a dog show match at Thomas Square. i showed my friend's golden retriever puppy, Toby, but before we went in the ring, we had to groom him. as i lifted Toby on the grooming table, i realized this had something to do with physics! since work equals the change in energy, i could calculate the work i did with the equation, w= mgh. m would be Toby's mass, g= 9.8 m/s2 and h would be the distance from the ground to the surface of the grooming table. the work done by gravity would be negative mgh in units of Joules. i could also calculate my power by dividing the work i did by the time it took me to lift Toby from the ground onto the table. although i didnt get a picture of me lifting Toby, i found one of another dog, Beau, on the grooming table. assuming that the height from the ground to the grooming table are the same in both cases, the work i did by lifting Beau would be less because his mass is less.

MUSIC BOOKS AND ENERGY

every saturday i have violin lessons. before i leave the house, i always place my music books at the top of the stairs so i dont forget them. i also place my violin case on the ground next to the stairs. this week, we learned about potential and kinetic energy. as i placed my music on the railing, i realized it had something to do with physics. the music's gravitational potential energy can be calculated by the equation mgh. so it would be its weight times the height of the railing. kinetic energy is the energy of motion. it can be calculated by the equation 1/2 mv squared. in this case, since the music books are not moving, there is no kinetic energy. as for the violin case, since it is on the ground, h=0 so it would not have any potential energy. the violin case is not moving so its kinetic energy would also be 0.