Explanation:
"Static friction is a force that keeps an object at rest. It must be overcome to start moving the object."
(556 x 0.68) = static friction of 378.08N. before movement occurs.
The forces (a) and (b) will not move it.
Each will incur a frictional force preventing movement equal to itself, = 222N. and 334N. respectively.
Forces (c) and (d) will move it, and accelerate it.
Forces (c) and (d) will both encounter friction of (556 x 0.56) = 311.36N. when the cabinet is moving.
Answer:
2.1 rad/s
Explanation:
Given that,
Mass of a tether ball, m = 0.546 kg
Length of a rope, l = 4.56 m
The maximum tension the rope can withstand before breaking is 11.0 N
We need to find the maximum angular speed of the ball. Let v is the linear velocity. The maximum tension is balanced by the centripetal force acting on it. It can be given by :

Let
is the angular speed of the ball. The relation between the angular speed and angular velocity is given by :

So, the maximum angular speed of the ball is 2.1 rad/s.
Answer:
B = 38.2μT
Explanation:
By the Ampere's law you have that the magnetic field generated by a current, in a wire, is given by:
(1)
μo: magnetic permeability of vacuum = 4π*10^-7 T/A
r: distance from the center of the cylinder, in which B is calculated
Ir: current for the distance r
In this case, you first calculate the current Ir, by using the following relation:

J: current density
Ar: cross sectional area for r in the hollow cylinder
Ar is given by 
The current density is given by the total area and the total current:

R2: outer radius = 26mm = 26*10^-3 m
R1: inner radius = 5 mm = 5*10^-3 m
IT: total current = 4 A
Then, the current in the wire for a distance r is:
(2)
You replace the last result of equation (2) into the equation (1):

Finally. you replace the values of all parameters:

hence, the magnitude of the magnetic field at a point 12 mm from the center of the hollow cylinder, is 38.2μT
Answer:
acceleration 8 km/h/s south
Explanation:
First of all, let's remind that a vector quantity is a quantity which has both a magnitude and a direction.
Based on this definition, we can already rule out the following two choices:
distance: 40 km
speed: 40 km/h
Since they only have magnitude, they are not vectors.
Then, the following option:
velocity: 5 km/h north
is wrong, because the car is moving south, not north.
So, the correct choice is
acceleration 8 km/h/s south
In fact, the acceleration can be calculated as

where
v = 40 km/h is the final velocity
u = 0 is the initial velocity
t = 5 s is the time
Substituting,

And since the sign is positive, the direction is the same as the velocity (south).
Answer:
60.2 J
Explanation:
Efficiency is the ratio of work out to work in.
e = Wout / Win
0.86 = Wout / 70 J
Wout = 60.2 J