Answer:
a
The time it would take the beef to reach a temperature of 0⁰C is t= 662 sec = 11.93 min
b)
The time it would take to heat the beef to uniform temperature of 80⁰C is
t = 365 sec =5.93 min
c
Efficient absorption of Microwave power is in regions of liquid water . Hence if the food or the microwave irradiation is not uniform, the power will be absorbed non-uniformly, resulting in a non-uniform temperature rise. Defrost region will absorb more energy per unit volume than frozen region.if food is of low thermal conductivity, there will be insufficient time for heat conduction to make the temperature more uniform.Use of low power allows more time for conduction to occur.
Explanation:
The explanation is shown on the first second and third uploaded image
Answer:
29.7 m/s fast, velocity is 29.7 m/s
Explanation:
Applying,
v² = u²+2gs...................... Equation 1
Where v = final velocity, u = initial velocity, g = acceleration due to gravity, s = distance.
Given: u = 0 m/s (dropped from height), s = 45 m
Constant: g = 9.8 m/s²
Substitute these values into equation 1
v² = 0²+2×9.8×45
v² = 882
v = √(882)
v = 29.7 m/s.
Hence the stone will be moving 29.7 m/s fast and the velocity is also 29.7 m/s
The efficiency of the machine is defined as

Here
Work out is the work output and Work in is the work input
To find the Work in we have then


Replacing with our values


The work done by the applied force is
W = Fd
Here,
F = Force
d = Distnace
Rearranging to find F,


F = 129.77N
Therefore the force exerted on the machine after rounding off to two significant figures is 130N