The answer is d
F=ma. so by substituting we find that a=4
and a=vi-vf/t
by substiting we find vf=8
so the difference is vf-vi = 8m/s
Answer:
A) True B) False C) True
Explanation:
To understand this concept we need to plan the equations related to the movement in the X-axis and the Y-axis thus we can see the behavior of the particle under the different forces.
In the attached image we can check the equation related with the forces.
A) The sum of the forces is 0 in both axis, therefore there is no movement of the particle.
B) In the previous point, we figure out that there is no movement and therefore no acceleration effect.
C) If a body or particle is not accelerating it will be in equilibrium or traveling at a constant velocity.
Initial velocity (u) = 90km/hr = 90/3.6 m/s = 25m/s
final velocity (v) = 18km/hr = 18/3.6 m/s = 5m/s
acceleration = (v-u)/t = (5-25)/4 = -5 m/s2
change in momentum = m(v-u) = 1200(5-25) = -24000 kg•m/s
F = ma = 1200 x -5 = -6000 N
The correct word to fill in the blank is:
<u>eccentric </u>
<u>
</u>Basing from the force-velocity curve, there are 2 muscle
actions, the concentric (shortening) and eccentric (lengthening). In eccentric
or lengthening muscle actions, force is high when the velocity is high. This is
opposite to concentric or shortening muscle actions, force is low when the
velocity is high. This means that in strength-gaining activities, the speed of
exercise should be slow during contraction, and it should be high when there is
expansion.