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Question

A box slides down a 34.0° ramp with an acceleration of 1.22 m/s2. Determine the coefficient of kinetic friction between the box and the ramp.
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A person pushes a shopping cart with a force of 91 N acting down at 45°. If the cart travels at a constant speed of 1.4 m/s, what is the value of the combined retarding force acting horizontally on the cart due to friction and air drag? [Hint: It is the horizontal component of the force that drives the cart forward. The constant speed tells you that Fx = ma = 0.]
N
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You slide a 325-N trunk up a 19.0° inclined plane with a constant velocity by exerting a force of 213 N parallel to the plane.
(a) What is the component of the trunk's weight parallel to the plane?
N
(b) What is the sum of your applied force, friction, and the parallel component of the trunk's weight?
N
Why?

Answer 1

You should only ask one question at a time.

I will answer the first:

Consider the forces on the box:

Gravity vertically downward
friction pulling backwards
The force of gravity parallel to the ramp
minus the force of friction
=m*a=m*1.22
so
m*sin(34)*g-f=m*1.22
friction can be expressed as
f=m*u*cos(34)*g
note that mass divides out
sin(34)*g-u*cos(34)*g=1.22

u=.52

j

Answer 2

I choose the 3rd one:
a) 325-N*SomeTrigFunction(19) You probably know that much.
Which trig function? Take the situation to extremes temporarily. If the angle was zero (surface is horizontal), there would be no component parallel with the surface - right? Which trig function is zero at zero degrees? sin. So
325-N*sin(19)

b) The sum is zero. Because the velocity is constant - no acceleration means no net force. F=ma

Answer 3

the galaxies rotate at speeds inconsistent with their obvious mass is with the help of the fact we do see all of it. i'm bearing on it as being the theoretical dark count number. There are very sturdy proofs that shows that dark count number exist. One the is the inconsistent velocity of and obvious mass. dark count number makes up approximately seventy 5% to 80% of the difficulty interior the Universe...