Answer:
A stone on the ground does not have zero energy…there is an internal potential in every object. Aldo is not in action or in any mechanical motion it is being acted upon by gravity and also molecular forces and energy.
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Answer:
Yes
Explanation:
An increased speed will result in an increased amount of energy, so when it crashes some of that energy will bounce back and crumple the car.
Answer:
The dentist uses X-ray radiography, which takes too short a time to cause those problems.
Explanation:
I took the test on Edg
Answer:
17.64 N
Explanation:
Draw a free body diagram (see attached). At the center of the ladder is weight pulling down. At point C, we have a normal force pushing perpendicular to the ladder. At point A, we have reaction forces in the x and y directions.
For simplicity, we can divide the normal force into x and y components. The slope of the ladder is -80/60, so the slope of the normal force is 60/80. Therefore:
Ny / Nx = 60 / 80
Ny / Nx = 3/4
Next, we'll take the sum of moments at point A:
∑τ = Iα
-Wd + Ny (60) + Nx (80) = 0
d is the horizontal distance between A and the center of the ladder. We can find it using similar triangles. From Pythagorean theorem, we know the distance between A and C is 100 cm. So:
60 / 100 = d / 60
d = 36
-(5)(9.8)(36) + Ny (60) + Nx (80) = 0
60 Ny + 80 Nx = 1764
We now have two equations and two variables. Solving:
60 (3/4 Nx) + 80 Nx = 1764
45 Nx + 80 Nx = 1764
125 Nx = 1764
Nx = 14.112
Ny = 3/4 Nx
Ny = 10.584
Using Pythagorean theorem to find N:
N = √(Nx² + Ny²)
N = 17.64
The magnitude of the normal force is 17.64 N.