Answer:
T_final = 279.4 [°C]
Explanation:
In order to solve this problem, we must use the following equation of thermal energy.

where:
Q = heat = 9457 [cal]
m = mass = 79 [g] = 0.079 [kg]
Cp = specific heat = 0.5 [cal/g*°C]
T_initial = initial temperature = 40 [°C]
T_final = final temperature [°C]
![9457 = 79*0.5*(T_{f}-40)\\239.41=T_{f}-40\\\\T_{f}=279.4[C]](https://tex.z-dn.net/?f=9457%20%3D%2079%2A0.5%2A%28T_%7Bf%7D-40%29%5C%5C239.41%3DT_%7Bf%7D-40%5C%5C%5C%5CT_%7Bf%7D%3D279.4%5BC%5D)
38 = 300
60 = ?
300 × 60 ÷ 38
1800 ÷ 38 = 47.368
The answer is 47.4 m per hour
This is true, The total energy when a body falls freely towards earth remains constant.
As per Newton's law when unbalanced force is acting on the object

so acceleration of the object is given as

since object is accelerating here so we can say that due to unbalanced force there must be change in velocity of the object
So correct answer regarding change in velocity must be given as
<u>3. Decelerate
</u>
<u>4. Stop moving
</u>
<u>5. Accelerate
</u>
<u>7. Start moving</u>