Answer:
fr ’= ½ F
Explanation:
For this exercise we use the translational equilibrium equation, on the axis parallel to the wall
fr - W = 0
fr = W
for the adult man they indicate that the friction force is equal to F
F = M g
we write the equilibrium equation for the child
fr ’= w’
fr ’= m g
in the statement they tell us that the mass of the adult is 2 times the mass of the child
M = 2m
we substitute
fr ’= M / 2 g
fr ’= ½ Mg
we substitute
fr ’= ½ F
therefore the force of friction in the child is half of the friction in the adult
Answer:
P = 75 W
Explanation:
given,
Distance, L = 8 m
Force,F = 150 N
Time, t = 16 s
Work by the climber
Work done = Force x displacement
W = F. L
W = 150 x 8
W = 1200 J
We know,


P = 75 W
Hence, Power climber is using to climb is equal to 75 W.
Answer:
The horizontal component of the truck's velocity is: 23.70 m/s
The vertical component of the truck's velocity is: 3.13 m/s
Explanation:
You have to apply trigonometric identities for a right triangle (because the ramp can be seen as a right triangle where the speed is the hypotenuse), in order to obtain the components of the velocity vector.
The identities are:
Cosα= 
Senα= 
Where H is the hypotenuse, α is the angle, CA is the adjacent cathetus and CO is the opposite cathetus
The horizontal component of the truck's velocity is:
Let Vx represent it.
In this case, CA=Vx, H=24 and α=7.5 degrees
Vx=(24)Cos(7.5)
Vx=23.79 m/s
The vertical component of the truck's velocity is:
Let Vy represent it.
In this case, CO=Vy, H=24 and α=7.5 degrees
Vy=(24)Sen(7.5)
Vy=3.13 m/s
C) is correct
series circuit - in the same path : current flow on one path so they are equal on each component and equal to the source's. voltage on each components may be different.
parallel circuit - between same nodes : voltage of the components are equal and equal to the source's. current on each components may be different.