Answer:
At constant pressure
Explanation:
Enthalpy of a system may be defined as the system's internal energy in addition to the product of the volume and pressure of the system.
It can be regarded as the system's capacity of heat transfer and to do non- mechanical work.
The enthalpy of the system at constant pressure gives the amount of heat or energy that is either absorbed by the system or released by the system.
Answer:
2.06 x 10⁴ J
Explanation:
The process takes place in three steps. First, the ice is heated from -20 °C to 0 °C. Then the ice undergoes a phase change to water. Finally, the water is heated from 0 °C to 50 °C.
The heat energy required for the first step is as follows:
Q = mcΔT = (36.0 g)(2.00 Jg⁻¹°C⁻¹)(0 °C - (-20 °C)) = 1440 J
The heat energy required for the phase change (where L is the heat of fusion) is then calculated. Grams are converted to moles using the molar weight of water (18.02 g/mol)
Q = ML = (36.0 g)(mol/18.02g)(6000 J/mol) = 11987 J
Finally, the heat energy required to raise the temperature of the water to 50°C is calculated:
Q = mcΔT = (36.0 g)(4.00 Jg⁻¹°C⁻¹)(50 °C - 0 °C) = 7200 J
Adding all of the heat energy values together gives:
(1440 + 11987 + 7200) J = 20627 J
The final answer is 2.06 x 10⁴ J
Answer:
1 and 3
Explanation:
At the point of hitting the tennis ball by the racquet, the force by the hit is acting on the ball.
Since there is a strong wind, the force exerted by the air will act on the tennis ball as it journeys to the ground in the opponents court.
Also, since the tennis ball undergoes a downward motion before it touches the ground, a downward force of gravity also acts on the ball.
After the tennis ball has left contact with the racquet, the force by the hit ceases to act on the ball since they are no longer in contact. However, <em>the downward force of gravity and the force exerted by the air still act on the tennis ball before it touches the ground. </em>
Therefore, the correct choice is:
1 and 3
Answer:
d = ( -0.3 , 0.7 ) miles
Explanation:
The complete question is as follows:
" Take the north direction as the positive y direction and east as positive x. The origin is still where the student starts biking. Let d⃗ N be the displacement vector corresponding to the first leg of the student's trip. Express d⃗ N in component form.
Express your answer as two numbers separated by a comma (e.g., 1.0,2.0). By convention, the x component is written first.
A student bikes to school by traveling first dN = 0.800 miles north, then dW = 0.300 miles west, and finally dS = 0.100 miles south. "
Solution:
- The displacement vector d N is vector sum of all journeys. We will express +x as +i and +y as +j. Then displacement vector is given by:
d = dN + dW + dS
d = 0.8 j - 0.3 i - 0.1 j
d = - 0.3 i + 0.7 j
- The displacement vector d in component form is d = ( -0.3 , 0.7 ) miles