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6physHW15

# 6physHW15 - A portable CD player uses a current of 15 mA at...

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Unformatted text preview: A portable CD player uses a current of 15 mA at a potential difference of 3.5 V. (a) How much energy does the player use in 35 s? {b} Suppose the player has a mass of (1.65 kg. For what length of time could the player operate on the energyr required to lift: it through a height of 1.0 n1? Picture the Problem: A portable CD player consumes electrical power as it operates. Strategy: The power consumed by the CD player equals the amount ofcurrent it draws multiplied by the electrical potential at which the current is delivered {equation 2|-4]. We can use the power it consumes to ﬁnd the amount oi" energy it uses in a speciﬁed time interval. We can also calculate the time it would take to increase the gravitational potential energy of the player if it converts electrical energy to mechanical energy at the same rate or power. Solution: |. {I} Find F from equation 2|—4.' l" = fl“ = [:15 I IllI "' .r’i “3.5 Vl= (1.026 W I. l[Calculate the energy consumed in 35 s: E = For = [if-“.3215 WH35 s} = it'll .l 0.55 k- 9.31m-’51 Le m =£=EEM=34M=- 3. I} F' d I ' ' ' . : a: t] it] ttetlnterequlredtollﬁlﬂm P ”3 [llﬂﬂlﬁatiﬂlﬁhﬂ Insight: Size an alkaline batteries rated at 28m met-h would operate this player for about 3?!) hours before needng to be replaced. ...
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