Physics Year End Review

KEY Physics 1.) What does the word energy mean? The ability to do work. That is the ability to cause a change to objects. 2.) List six different forms energy can be in and give examples of objects that have these forms of energy. Nuclear = nuclear power plant Elastic = rubber ball Electrical = lightning Chemical = food Mechanical = fan Sound = speaker 3.) List three common sources of energy in BC and include a positive and negative aspect of each form. Coal - positive = cheap/negative = high pollution rate Natural gas – positive = cheap/negative = produces global warming gases (CO2) Electricity – positive = minimal global warming gases/negative = damages ecosystems 4.) State the entire law of conservation of energy. Energy cannot be created nor destroyed, only transformed. 5.) Write a short equation that embodies the answer of the statement you wrote in question 4. 6.) Write down the equation for stored energy and list what each variable stands for, with its unit. where Potential energy - is the mass ( 9.81 ), and ), is the acceleration from gravity is the height ( ) above the surface of the earth. 7.) Write down the equation for the energy of motion and list what each variable stands for, with its unit. where Kinetic energy 8.) a.) A 3.0 is the mass ( is the velocity ( ). scrub jay is squawking in an oak tree in Mrs. Fifield’s backyard. If the bird is on a branch located 20.0 from the ground, how much potential energy does it have? 3.0 9.81 20.0 b.) If a 6.0 ), and 588.6 scrub jay were sitting on the same branch as the first jay, his would be: i. The same as the first jay. ii. Two times the of the first jay. iii. Four times the of the first jay. iv. One-half the of the first jay. 9.) A squirrel in a nearby tree drops an acorn and just misses Mrs. Sargent’s dog, Caesar. If the acorn has 255.5 of potential energy and a mass of 1.0 255.5 1.0 9.81 , how high up is the branch from which the acorn fell? 26.0 KEY 10.) A gymnast exercises by jumping on a trampoline. At her highest point she is 4.3 off the ground and has a potential energy of 11466 . What is the mass of the gymnast? 11466 9.81 4.3 11.) a.) A boy is ready to drop a 1.6 the balloon 11.3 271.82 water balloon out of a window onto his sister below. The boy is holding off the ground. How much potential energy does the balloon have just before the boy drops it? 1.6 9.81 11.3 177.36 b.) If the boy were holding the same balloon at a height of 33.9 off the ground, its would be: i.) The same as the balloon at the lower height. ii.) Three times the iii.) Nine times the iv.) One-third the of the balloon at the lower height. of the balloon at the lower height. of the balloon at the lower height. c.) How much potential energy will the balloon have right before it hits the boy’s sister? Explain. Zero. The balloon no longer contains any height. The energy has been transformed completely into kinetic energy. 12.) A roller coaster is at the top of a 72 hill and weighs 966 . The coaster (at this moment) has __potential_ energy. Calculate it. . 13.) A car is traveling with a velocity of 40. it. 9.81 72 and has a mass of 1120 0.5 1120 40 . The car has _kinetic_ energy. Calculate 996 000 14.) Two objects were lifted by a machine. One object had a mass of 2.0 2.0 . The other had a mass of 4.0 96 552 , and was lifted at a speed of and was lifted at a speed of 3.0 . a.) Which object had more kinetic energy while it was being lifted? 0.5 2.0 2.0 4.0 0.5 1120 40 18.0 b.) Which object had more potential energy when it was lifted to a distance of 10. calculation. 2.0 9.81 10. 4.0 9.81 10. 392.4 196.2 ? Show your