Chemical energy stored in the compounds caked on the head of the match, and later the
chemical energy stored in the wood, was released in the form of heat and light when the
chemical compounds got hot enough.
Answer:
the claim is not valid or reasonable.
Explanation:
In order to test the claim we will find the maximum and actual efficiencies. maximum efficiency of a heat engine can be found as:
η(max) = 1 - T₁/T₂
where,
η(max) = maximum efficiency = ?
T₁ = Sink Temperature = 300 K
T₂ = Source Temperature = 400 K
Therefore,
η(max) = 1 - 300 K/400 K
η(max) = 0.25 = 25%
Now, we calculate the actual frequency of the engine:
η = W/Q
where,
W = Net Work = 250 KJ
Q = Heat Received = 750 KJ
Therefore,
η = 250 KJ/750 KJ
η = 0.333 = 33.3 %
η > η(max)
The actual efficiency of a heat engine can never be greater than its Carnot efficiency or the maximum efficiency.
<u>Therefore, the claim is not valid or reasonable.</u>
Answer:
Electric field, 
Explanation:
It is given that,
Mass of sphere, m = 2.1 g = 0.0021 kg
Charge, 
We need to find the magnitude of electric field that balances the weight of a plastic spheres. So,
a = g
or
Hence, the magnitude of electric field that balances its weight is 
. Hence, this is the required solution.
Explanation:
F = ma, and a = Δv / Δt.
F = m Δv / Δt
Given: m = 60 kg and Δv = -30 m/s.
a) Δt = 5.0 s
F = (60 kg) (-30 m/s) / (5.0 s)
F = -360 N
b) Δt = 0.50 s
F = (60 kg) (-30 m/s) / (0.50 s)
F = -3600 N
c) Δt = 0.05 s
F = (60 kg) (-30 m/s) / (0.05 s)
F = -36000 N
<span>37.8 seconds
First, determine the speed difference between the car and truck.
95 km/h - 75 km/h = 20 km/h
Convert that speed into m/s to make a more convenient unit of measure.
20 km/h * 1000 m/km / 3600 s/h = 5.556 m/s
Now it's simply a matter of dividing the distance between the two vehicles and their relative speed.
210 m / 5.556 m/s = 37.8 s
So it will take 37.8 seconds for the car to catch the truck that's 210 meters in front of the car.</span>
