Angular Momentum Angular Momentum MOMENTUM RESULTING FROM AN

  • Slides: 20
Download presentation
Angular Momentum

Angular Momentum

Angular Momentum • MOMENTUM RESULTING FROM AN OBJECT MOVING IN LINEAR MOTION IS CALLED

Angular Momentum • MOMENTUM RESULTING FROM AN OBJECT MOVING IN LINEAR MOTION IS CALLED LINEAR MOMENTUM. • MOMENTUM RESULTING FROM THE ROTATION (OR SPIN) OF AN OBJECT IS CALLED ANGULAR MOMENTUM.

Conservation of Angular Momentum • ANGULAR MOMENTUM IS IMPORTANT BECAUSE IT OBEYS A CONSERVATION

Conservation of Angular Momentum • ANGULAR MOMENTUM IS IMPORTANT BECAUSE IT OBEYS A CONSERVATION LAW, AS DOES LINEAR MOMENTUM. • THE TOTAL ANGULAR MOMENTUM OF A CLOSED SYSTEM STAYS THE SAME.

Calculating angular momentum ANGULAR MOMENTUM IS CALCULATED IN A SIMILAR WAY TO LINEAR MOMENTUM,

Calculating angular momentum ANGULAR MOMENTUM IS CALCULATED IN A SIMILAR WAY TO LINEAR MOMENTUM, EXCEPT THE MASS AND VELOCITY ARE REPLACED BY THE MOMENT OF INERTIA AND ANGULAR VELOCITY. ANGULAR MOMENTUM (KG M/SEC 2) L=Iw Moment of inertia (kg m 2) Angular velocity (rad/sec)

Calculating angular momentum An artist is making a moving metal sculpture. She takes two

Calculating angular momentum An artist is making a moving metal sculpture. She takes two identical 1 kg metal bars and bends one into a hoop with a radius of 0. 16 m. The hoop spins like a wheel. The other bar is left straight with a length of 1 meter. The straight bar spins around its center. Both have an angular velocity of 1 rad/sec. Calculate the angular momentum of each and decide which would be harder to stop. 1. You are asked for angular momentum. 2. You are given mass, shape, and angular velocity. – 3. Hint: both rotate about y axis. Use L= I , Ihoop = mr 2, Ibar = 1/12 ml 2

TORQUE

TORQUE

WHEN QUARTERBACKS THROW THE FOOTBALL, THEY IMPART A SPIN WITH THEIR FINGERS, SO THAT

WHEN QUARTERBACKS THROW THE FOOTBALL, THEY IMPART A SPIN WITH THEIR FINGERS, SO THAT THE BALL SPINS RAPIDLY AS IT FLIES THROUGH THE AIR. FOOTBALL FANS CALL A GOOD PASS A TIGHT SPIRAL.

BULLETS WHICH COME OUT OF A RIFLED BARREL HAVE GROOVES CUT INTO THEM, LIKE

BULLETS WHICH COME OUT OF A RIFLED BARREL HAVE GROOVES CUT INTO THEM, LIKE THIS ONE. THESE LEAVE BALLISTIC FINGER PRINTS

ANGULAR MOMENTUM

ANGULAR MOMENTUM

Calculating angular momentum 3. Solve hoop: Ihoop= (1 kg) (0. 16 m)2 = 0.

Calculating angular momentum 3. Solve hoop: Ihoop= (1 kg) (0. 16 m)2 = 0. 026 kg m 2 – Lhoop= (1 rad/s) (0. 026 kg m 2) = 0. 026 kg m 2/s 4. Solve bar: Ibar = (1/12)(1 kg) (1 m)2 = 0. 083 kg m 2 – Lbar = (1 rad/s) (0. 083 kg m 2) = 0. 083 kg m 2/s 5. The bar has more than 3 x the angular momentum of the hoop, so it is harder to stop.

12. 3 Gyroscopes angular momentum • A gyroscope is a device that contains a

12. 3 Gyroscopes angular momentum • A gyroscope is a device that contains a spinning object with a lot of angular momentum. • Gyroscopes can do amazing tricks because they conserve angular momentum. • For example, a spinning gyroscope can easily balance on a pencil point.

12. 3 Gyroscopes angular momentum • A gyroscope on the space shuttle is mounted

12. 3 Gyroscopes angular momentum • A gyroscope on the space shuttle is mounted at the center of mass, allowing a computer to measure rotation of the spacecraft in three dimensions. • An on-board computer is able to accurately measure the rotation of the shuttle and maintain its orientation in space.