Answer:
A.
Explanation:
All the arrows align to the point right
From Carnot's theorem, for any engine working between these two temperatures:
efficiency <= (1-tc/th) * 100
Given: tc = 300k (from question assuming it is not 5300 as it seems)
For a, th = 900k, efficiency = (1-300/900) = 70%
For b, th = 500k, efficiency = (1-300/500) = 40%
For c, th = 375k, efficiency = (1-300/375) = 20%
Hence in case of a and b, efficiency claimed is lesser than efficiency calculated, which is valid case and in case of c, however efficiency claimed is greater which is invalid.
Among the choices the one that most likely cause a sound wave is C or the a spoon hitting the side of a bowl while mixing <span>because that's going to make a sound.
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v2 = ?
m1 = 10kg
m2 = 70kg
v1 = 4m/s
E1 = E2
E1 = 1/2 * m1 * v1^2 = 1/2 * 10kg * 4m/s^2 = 80J
E2 = 1/2 * m2 * v2^2 = 80 J
v2 = √(E2/(2 * m2)) = √(80J/(2 * 70kg)) = about 0.76m/s
<span>the spring constant is 200kN/m.
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The work done on the spring by the the free falling safe is equal to the kinetic energy of the spring:
W1 =

k

The work done on the safe by gravity is the potential energy of the spring:
W2 = (mass of safe) x g x (height)
= 1000kg x 9.8 m/s^2 x (2 + 0.54)m
=1000kg x 9.8 m/s^2 x (2.54)m
= 24,892 N-m
W2 = W1 =24892 N-m
⇒

k

= 24892 N-m
Therefore, k =

= 199136 kN/m.
The spring constant is 199,136 N/m ≈ 200 kN/m