11. -3 points SerCP11 11P002. A medium-sized pear provides about 102 Calories of

Question

11. -3 points SerCP11 11P002. A medium-sized pear provides about 102 Calories of energy HINT (a) Convert 102 Cal to joules. (b) Suppose that amount of energy is transformed into kinetic energy of a 2.23 kg object initially at rest. Calculate the final speed of the object (in m/s) (c) f that same amount of energy is added to 3.79 kg (about 1 gal) of water at 21.7°c, what is the water's final temperature (in °C)? The specific heat of water is c-4186 (kg °c) oC Need Help? Read t Submit Answer Save Progress Practice Another Version

Explanation / Answer

a)

1 Cal = 1000 cal

and

1 cal = 4.184 J

So,

102 Cal = 102*1000*4.184 J

= 4.27*10^5 J

Answer: 4.27*10^5 J

b)

Now use:

KE = 0.5*m*v^2

4.27*10^5 J = 0.5*(2.23 Kg)*v^2

v^2 = 3.83*10^5

v = 619 m/s

Answer: 619 m/s

c)

use:

Q = m*C*(Tf-Ti)

4.27*10^5 J = 3.79 Kg * (4186 J/Kg.oC)*(Tf-21.7)

Tf-21.7 = 26.9

Tf = 48.6 oC

Answer: 48.6 oC

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