Answer:
a third class lever
Explanation:
The third class or interpower lever is a lever that enables fast and dynamic movements. It places the power between the resistance and the support, so the resistance arm is longer than the power.
It is the most frequent type of lever in the human body and as an example we can put the action of the brachial biceps in the flexion of the elbow, where the biceps is inserted in the forearm between the elbow that is behind and the resistance that would be displaced towards the hand by the weight of the load attached to the weight of the forearm.
A good range of movements is achieved although with less force and is the most frequent type of lever in human movement, although the same joint can form different types of lever depending on the type of movement performed
.
Answer:
D) Acceleration is positive and increasing.
Explanation:
Acceleration is defined as the rate of change of velocity per unit time; in formulas:
where 
is the variation of velocity and 
is the variation in time.
The graph shows the velocity vs the time of a moving object. We can see that is the increment on the y-axis, while is the increment on the x axis: therefore, the ratio 
is the slope of the curve. In fact, in a velocity-time graph, the slope of the curve corresponds to the acceleration of the object.
In this particular graph, we see that the slope of the curve continues to increase: therefore, the acceleration is positive (because the slope is positive, since the velocity is increasing) and increasing (because the slope is increasing).
Answer:
The work done in pulling the bucket to the top of the well is 3,360 ft-lb
Explanation:
Given
Weight = 6 lb
Depth = 80ft
Weight of Water = 40lb
Rate = 2ft/s
Leak Rate = 0.2ft/s
Calculating Workdone to lift the bucket
Work = Force * Distance
Work = 6 * 80
Work = 480ft-lb
At time t, the bucket is xi = 2t above the original depth of 80ft.
t = ½xi
But it now holds 40lb - 0.2t lb of water
= 40 - 0.2(½xi)
= 40 - 0.1xi.
This is the size of the water when it is x ft above the original depth.
To move this amount of water, we need (40 - 0.1xi)∆x
So, W = ∫(40 - 0.1xi)∆x {1,n}
Where n = 80
W = ∫(40 - 0.1x)dx {0,80}
W = 40x - ½(0.1x²) {0,80}
W = 40x - x²/20 {0,80}
W = 40(80) - 80²/20
W = 3200 - 320
W = 2880 ft-lb
The work done in pulling the bucket to the top of the well = 2880 + 480
= 3,360 ft-lb
Answer:
A : A restoring force acts on an object in simple harmonic motion that is directed in the same direction as the object's displacement.
Explanation:
Statement A is the false one:
A : A restoring force acts on an object in simple harmonic motion that is directed in the same direction as the object's displacement. --> FALSE. The restoring force in the simple harmonic motion is given by
where
k is the spring constant
x is the displacement of the system, measured with respect to the equilibrium position
As we can notice from the equation, there is a negative sign in front of (kx): this means that the force, F, and the displacement, x, have opposite directions. In fact, the restoring force of a simple harmonic oscillator always acts to restore the equilibrium position, therefore it acts in the opposite direction as that of the displacement.
