Complete question is;
Shoveling snow can be extremely taxing since the arms have such a low efficiency in this activity. Suppose a person shoveling a sidewalk metabolizes food at the rate of 800 W. (The efficiency of a person shoveling is 3%.)
(a) What is her useful power output? (b) How long will it take her to lift 3000 kg of snow 1.20 m? (This could be the amount of heavy snow on 20 m of footpath.) (c) How much waste heat transfer in kilojoules will she generate in the process?
Answer:
A) P_out = 24 W
B) t = 1470 s
C) Q = 1140.72 KJ
Explanation:
We are given;
Input Power; P_in = 800 W
Efficiency; η = 3% = 0.03
A) Formula for efficiency is;
η = P_out/P_in
Making P_out the subject, we have;
P_out = η•P_in
P_out = 0.03 × 800
P_out = 24 W
B) We know that;
Power = work done/time taken
Thus;
P_out = mgh/t
We are given;
m = 3000 kg
h = 1.20 m
Thus, time is;
t = (3000 × 9.8 × 1.2)/24
t = 1470 s
C) amount of heat wasted is calculated from;
Q = (P_in - P_out)t
Q = (800 - 24) × 1470
Q = 1,140,720 J
Q = 1140.72 KJ
Answer: 586.60N/m
Explanation:
In this scenario, the elastic potential energy of the spring is converted into potential energy.
0.5*K*x^2 = mgh
Thus K = 2mgh/x^2
=(2*2.90*10^-2*9.8*7.23)/(8.37*10^-2)^2
=586.599
Therefore K = 586.60N/m
A projectile<span> is an object upon which the only force acting is gravity. Many </span>projectiles<span> not only undergo a vertical </span>motion<span>, but also undergo a horizontal </span>motion<span>. That is, as they move upward or downward they are also moving horizontally.</span>
Answer:
v(t) = 27 units
Explanation:
The function s(t) represents the position of an object at time t moving along a line such that,
and
We need to find the average velocity of the object over the interval of time [2,6]. The velocity of the object is equal to the total distance divided by time. It is given by :
v(t) = 27 units
So, the average velocity of the object is 27 units. Hence, this is the required solution.
<u>A</u> would be the answer, since it would take about 3 hours to cover most of it, 10km/h would be the average speed.
really hope this helps.
