1. You add 25 g of milk at 10?C to 200 g of coffee (essentially water) at 70?C .

Question

1. You add 25 g of milk at 10?C to 200 g of coffee (essentially water) at 70?C . The coffee is in a Styrofoam cup.

If the specific heat of milk is 3800 J/kg??C and the specific heat of coffee is 4180 J/kg??C by how much will the coffee temperature decrease when the milk is added?

2. A lead bullet of mass m traveling at vi penetrates a wooden block and stops.

Express your answer in terms of the variables m , vi and c.

3. A crate of fruit with a mass of 30.5kg and a specific heat capacity of 3750J/(kg?K) slides 7.50m down a ramp inclined at an angle of 39.8degrees below the horizontal.

Use 9.81 m/s2 for the acceleration due to gravity and express your answer in joules.

4. A canteen is covered with wet canvas.

If 15 g of water evaporates from the canvas and if 50% of the thermal energy used to evaporate the water is supplied by the 500 g of water in the canteen, what is the temperature change of the water in the canteen?

1. You add 25 g of milk at 10?C to 200 g of coffee (essentially water) at 70?C . The coffee is in a Styrofoam cup. If the specific heat of milk is 3800 J/kg??C and the specific heat of coffee is 4180 J/kg??C by how much will the coffee temperature decrease when the milk is added? 2. A lead bullet of mass m traveling at vi penetrates a wooden block and stops. Assuming that 50% Wt was done on the crate by friction? Use 9.81 m/s2 for the acceleration due to gravity and express your answer in joules. 4. A canteen is covered with wet canvas. If 15 g of water evaporates from the canvas and if 50% of the thermal energy used to evaporate the water is supplied by the 500 g of water in the canteen, what is the temperature change of the water in the canteen? m/s at the bottom, how much work Wf c, write an expression that would allow you to determine the bullet's temperature increase. Express your answer in terms of the variables m , vi and c. 3. A crate of fruit with a mass of 30.5kg and a specific heat capacity of 3750J/(kg?K) slides 7.50m down a ramp inclined at an angle of 39.8degrees below the horizontal. If the crate was at rest at the top of the incline and has a speed of 2.30m/s % of the initial kinetic energy of the bullet is converted into thermal energy in the bullet and the specific heat of lead is c

Explanation / Answer

1. Energy conservation

25*3800*(T-10) = 200*4180*(70-T)

T = 63.87 C

so decrease in temperature = 70-T = 6.12

2. thermal energy = 50% of initial kinetic enegy

so thermal enrgy = 0.5*0.5*m*vi^2 ....... eq1

so thermal enegy = m*c* delta T ........eq2

equating eq1 and eq2

0.25*m*vi^2 = m*c* delta T

delta T = 0.25*vi^2/c

equat

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