You have to move your 100 N couch before a delivery company drops off your new one. Unfortunately your roommate is passed out on it. The coefficient of friction between the couch and floor is .43. It takes 250 N of force to get the couch moving. a) How much does your roommate weigh in Newton’s? b) After you get the couch moving it only takes 200 N to keep it moving at a constant speed, what is the coefficient of kinetic friction?

a) Weight of Roommate = 481.4 N

b) μk = 0.34

Explanation:

a)

The force required to move the couch must be equal to the force of friction:

F = frictional force

F = μW

W = F/μ

where,

W = Total Weight of Couch and Roommate

F = Force Required start to move couch = 250 N

μ = coefficient of static friction between couch and floor = 0.43

Therefore,

So, the total weight is given as:

W = Weight of Couch + Weight of Roommate

Weight of Roommate = W - Weight of Couch

Weight of Roommate = 581.4 N - 100 N

Weight of Roommate = 481.4 N

b)

Now, the force required to keep the couch moving can be given as equal to the kinetic friction force:

F = kinetic friction

F = μk*W

μk = F/W

where,

μk = coefficient of kinetic friction = ?

F = Force required to keep the couch moving = 200 N

Therefore,

μk = 200 N/581.4 N

μk = 0.34

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

graphing motion: mastery test

209be

what is the instantaneous acceleration of

the particle at point b?

0 meters/second?

10 meters/second?

12 meters/second?

velocity imetersisecond

15 meters/second?

20

time (seconds)

answer: 0 meters/second^2