987 asked in Science & MathematicsPhysics · 1 month ago

# my question?

One rechargeable battery of mass 15.0 g delivers an average current of 18.0 mA to a compact disc player at 1.60 V for 2.40 h before the battery needs to be recharged. The recharger maintains a potential difference of 2.11 V across the battery and delivers a charging current of 13.5 mA for 4.20 h.

(a) What is the efficiency of the battery as an energy storage device? _

(b) How much internal energy is produced in the battery during one charge-discharge cycle?

ΔEint = _J

(c) If the battery is surrounded by ideal thermal insulation and has an overall effective specific heat of 975 J/kg°C, by how much will its temperature increase during the cycle?

ΔT = _°C

Relevance
• Anonymous
1 month ago

a)

e = Eout / Ein

e = 18*1.6*2.4 / (13.5*2.11*4.2) = 0.58 (58%)

b)

ΔEint = Ein - Eout

ΔEint = 13.5x10^-3*2.11*4.2*3,6x10^3 - 18x10^-3*1.6*2.4x3,6x10^3 = 181.86 J

c)

ΔEint = m c ΔT

ΔT = ΔEint / (m c)

ΔT = 181.86 / (15x10^-3* 975) = 12.43 C