Raising 100 grams of water from 40 to 60 °C (the specific heat capacity of water is 1
2 answers:
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Answer:
120°
Explanation:
Draw a free body diagram. There are three forces acting on the traffic light. Two tension forces acting along the cables, and weight.
The tension forces have an angle θ between them. That means each tension force forms an angle of θ/2 with respect to the vertical. So the y component of each tension force is:
Ty = T cos (θ/2)
Sum of the forces in the y direction:
∑F = ma
Ty + Ty − W = 0
2 Ty = W
Substituting:
2 T cos (θ/2) = W
If W = T, then:
2 W cos (θ/2) = W
2 cos (θ/2) = 1
cos (θ/2) = 1/2
θ/2 = 60°
θ = 120°
Answer:
4.18
Explanation:
Givens
The car's initial velocity = 0 and covering a distance Δx = 1/4 mi = 402.336 m in a time interval t = 4.43 s.
Knowns
We know that the maximum static friction force is given by:
μ_s*n (1)
Where μ_s is the coefficient of static friction and n is the normal force.
Calculations
(a) First, we calculate the acceleration needed to achieve this goal by substituting the given values into a proper kinematic equation as follows:
Δx=
a=41 m/s
This is the acceleration provided by the engine. Applying Newton's second law on the car, so in equilibrium, when the car is about to move, we find that:
Substituting (3) into (1), we get:
μ_s*m*g
Equating this equation with (4), we get:
ma= μ_s*m*g
μ_s=a/g
=4.18