1. WHAT IS ENERGY?

2. ENERGY ENERGY: ability to do work. Whenever work is done, energy is transformed or transferred to another system. SI Units: joules (J)

3. POTENTIAL ENERGY energy that an object has because of position, shape, or condition stored energy.

4. ELASTIC POTENTIAL ENERGY energy stored in any type of stretched or compressed elastic material. spring rubber band

5. GRAVITATIONAL POTENTIAL ENERGY energy stored in gravitational field which exists between any two or more objects. depends on both mass and height. PE = mgh

6. GRAVITATIONAL POTENTIAL ENERGY A 65 kg rock climber ascends a cliff. What is the climber’s gravitational potential energy at a point 35 m above the base of the cliff? GIVEN: m = 65 kg h = 35 m g= 9.8 m/s 2 PE = ? WORK : PE = mgh PE = (65 kg) (35 m) (9.8 m/s 2 ) PE = 2.2 x 10 4 kgm 2 /s 2 2.2 x 10 4 J

7. Kinetic Energy energy of a moving object due to object’s motion depends on mass and speed. depends on speed more than mass.

8. KINETIC ENERGY What is the kinetic energy of a 44 kg cheetah running at 31 m/s? GIVEN: KE = ? m = 44 kg v= 31 m/s WORK : KE = ½ mv 2 KE = ½ (44 kg) (31 m/s) 2 KE = 2.1 x 10 4 kg x m 2 /s 2 or 2.1 x10 4 J

9. KINETIC ENERGY Calculate the kinetic energy in joules of a 1500 kg car moving at 29 m/s. GIVEN: KE = ? m = 1500 kg v= 29 m/s WORK : KE = ½ mv 2 KE = ½ (1500 kg) (29 m/s) 2 KE = 6.3 x10 5 J

10. KINETIC ENERGY Calculate the kinetic energy in joules of a 1500 kg car moving at 18 m/s. GIVEN: KE = ? m = 1500 kg v= 18 m/s WORK : KE = ½ mv 2 KE = ½ (1500 kg) (18 m/s) 2 KE = 2.4 x10 5 J

11. OTHER FORMS OF ENERGY MECHANICAL ENERGY: amount of work an object can do because of object’s kinetic & potential energies you can SEE it Large scale basis NONMECHANICAL ENERGY. you CANNOT SEE it X rays, microwaves Small scale basis (atomic)

12. OTHER FORMS OF ENERGY ATOMS AND MOLECULES kinetic energy of particles related to heat and temperature. CHEMICAL REACTIONS Breaking bonds exothermic/endothermic PHOTOSYNTHESIS turn energy in sunlight into chemical energy.

13. OTHER FORMS OF ENERGY NUCLEAR FUSION /FISSION REACTIONS Combining or splitting of atomic nuclei ELECTRICITY. flow of charged particles bolt of lightning or in a wire. ELECTROMAGNETIC WAVES. Light energy (solar) from sun X rays