During an auto accident, the vehicle's air bags deploy and slow down the passengers more gently than if they had hit the windshi
1 answer:
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Answer:
a) 200m, 100m/s
b) 710.20m
c) -117.98 m/s
d) 26.24 s
Explanation:
To solve this we have to use the formulas corresponding to a uniformly accelerated motion problem:
(1)
(2)
(3)
where:
Vo is initial velocity
Xo=intial position
V=final velocity
X=displacement
a)
the intial position is zero because is lauched from the ground and the intial velocitiy is zero because it started from rest.
b)
The intial velocity is 100m/s we know that because question (a) the acceleration is -9.8 because it is going downward.
c)
In order to find the velocity when it crashes, we can use the formula (3).
the initial velocity is 0 because in that moment is starting to fall.
the minus sign means that the object is going down.
d)
We can find the total amount of time adding the first 4 second and the time it takes to going down.
to calculate the time we can use the formula (2) setting the reference at 200m:
solving this we have: time taken= 22.24 seconds
total time is:
total=22.24+4=26.24 seconds.
Answer:
The final equilibrium T_{f} = 25.7[°C]
Explanation:
In order to solve this problem we must have a clear concept of heat transfer. Heat transfer is defined as the transmission of heat from one body that is at a higher temperature to another at a lower temperature.
That is to say for this case the heat is transferred from the iron to the water, the temperature of the water will increase, while the temperature of the iron will decrease. At the end of the process a thermal balance is found, i.e. the temperature of iron and water will be equal.
The temperature of thermal equilibrium will be T_f.
The heat absorbed by water will be equal to the heat rejected by Iron.
Heat transfer can be found by means of the following equation.
where:
Qiron = Iron heat transfer [kJ]
m = iron mass = 200 [g] = 0.2 [kg]
T_i = Initial temperature of the iron = 300 [°C]
T_f = final temperature [°C]
Cp_iron = 437 [J/kg*°C]
Cp_water = 4200 [J/kg*°C]