Some work will be done on friction between wheels and road but it is negligible compared to work done on friction on breaks.
W = Ek = (m*v^2)/2 = 2000*22^2/2 = 1000*22^2 = 484KJ
Because car is not changing its potential energy, there is no work to be done on while changing it which means that all goes on changing kinetic energy (energy of motion)
Answer:
The electromagnetic wave that travels the fastest through space is gamma ray
Explanation:
Electromagnetic wave is a type of wave which does not require material medium for its propagation. Examples of electromagnetic waves according to increasing frequency of the waves are gamma ray, x-ray, ultra violet ray, infra red, visible light, micro wave and radio waves.
Frequency of a wave is inversely proportional to period of oscillation of the wave. The higher the frequency of a wave, the shorter the period of oscillation. Gamma ray has the highest wave frequency in electromagnetic spectrum and shorter period of oscillation, thereby causing it to have the highest penetration power.
3. It is not changing at that time
Explanation:
If the acceleration of a body is zero at some instant in time, it implies that the velocity is not changing at that point in time. Velocity is the rate of change of displacement with time.
✓Acceleration and velocity shares a very close relationship.
✓ For a body to accelerate, the velocity must change. Acceleration is defined as the rate of change of velocity with time.
✓If at any point, a body moves with constant velocity i.e the velocity does not change with time, the acceleration becomes zero.
✓ For acceleration to occur, a body must change velocity.
Learn more:
Acceleration brainly.com/question/6323625
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Most appropriate unit of measurement should be centimetres, cm.
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
