In general, the quantity of heat energy, Q, required to raise a mass m kg of a substance with a specific heat capacity of <span>c </span>J/(kg °C), from temperature t1 °C to t2 °C is given by:
<span>Q </span>= <span>mc(t</span><span>2 </span><span>– t</span>1<span>) joules</span>
<span>So:</span>
(t2-t1) =Q / mc
<span>As we know:
Q = 500 J </span>
<span>m = 0.4 kg</span>
<span>c = 4180 J/Kg </span>°c
<span>We can take t1 to be 0</span>°c
t2 - 0 = 500 / ( 0.4 * 4180 )
t2 - 0 = 0.30°c
Need more details to the question
125 W is the power output of this machine.
Answer:
Explanation:
Power is defined as the amount of work done on the system to move that system from its original state within the given time interval. So it can be determined by the ratio of work done with time interval. As work done is the measure of force required to move a system to a certain distance. Work done is calculated as product of force with displacement.
So in the present case, the force is given as 100 N, the displacement is given as 5 m and the time is given as 4 s, then power is
As Work done = Force acting on the machine × Displacement
So 
Power = 
=125 W
So, 125 W is the power output of this machine.
We are given the following:
Bobo's swimming speed = 2.0 m/s
Width of the river = 100 m
Flowrate of the river = 6.0 m/s due east
First, we need to illustrate the problem. Draw the river with a width of 100 meters. Then, the flow of the river, east at 6 meters per second. Lastly, draw Bobo at one side of the river facing north and an arrow representing swimming speed at 2 meters per second.
Now, we can use the Pythagorean theorem to solve this rate problem.
c^2 = a^2 + b^2
c = speed of Bobo needed
a = speed of Bobo facing north
b = flow rate of the river going east
c^2 = 2^2 + 6^2
c = 6.32 m / s should be his speed to overcome the current and make a landing at the desired location.
