PRACTICE PAGE (1)

Date Name fl /' CONCEPTUAL Ays c W Chapter 7 Energy Work and Energy 1. How much work (energy) is needed to lift an object that weighs 200 N to a height of 4 meters? oo T 2. How much power is needed to lift the 200-N object to a height of 4 m in 4 seconds? 20 (00 0Q wetls wotts 3. What is the power output of an engine that does 60,000 J of work in 10 seconds? 4. The block of ice weighs 500 newtons. (Neglect friction.) a. How much force parallel to the incline is needed to push it to the top? Z:CQ . b. How much work is required to push it to the top of the incline? _J"ii_ c. What is the potential energy of the block relative to ground level? _Isi_ [§e°T d. What would be the potential energy if the block were simply lifted vertically 3 m? 5. All the ramps below are 5 m high. We know that the KE of the block when reaching the bottom of each ramp will be equal to the loss of PE (conservation of energy). Find the speed of the block at ground level in each case. [Hint: Do you recall from earlier chapters how much time it takes something to fall a vertical distance of 5 m from a position of rest (assume g = 10 m/s?)? And how much speed a falling object acquires in this time? This gives you the answer to Case 1. Discuss with your classmates how energy conservation provides the answers to Cases 2 and 3.] ’ oo 5"‘: Ral__ Case 1 SpeedM m/s Speed 9127 m/s S omt g — — 35

Chapter 7 Energy Work and Energy—continued 6. Which block gets to the bottom of the incli Sle shown in only one place in the sketch. values. PE=/S KE=0 pPE= 50 J KE=29 . s due to gravity along @ rts from rest at the top of ‘thg in the sketch. How fast is it 8. A big metal bead slide: friction-free wire. It sta wire, Point A, as shown traveling as it passes Point B2 [0 "7 ro l\\‘,‘( PointD? "~ i M/ Point E? q Maximum speed occurs at Point s S 9. Rows of wind-p CoN CEPfiTUAL hy s i‘ m{(_——\ ne first? Assume no A eca(ge Twe ST LT 7. The KE and PE of a block freely sliding down 2 ramp are Fill in the missing n upright Jocations to generate elect affect the speed of the win friction. (Be carefull) Explain, B ’ 4 ’, A owered generators are used in various windy ric power. Does the power generated d? That is, would locations behind the dmills weren't there? Discuss this in SRRV ) Y, out 16 6 +/°C s, W, Nndmi g