All categories

3 years ago

A 55 kg roller skater is at rest on a flat skating rink, a 198 N horizontal force is needed to set the skater in motion.

Physics

1 answer:

Rufina [12.5K]3 years ago

8 0

Answer:

Explanation:

To get the person Moving you have to overcome the static (means not moving) friction coefficient. U(static)

To get the person going at the same speed you have to overcome the kinetic friction coefficient. U(Kinetic)

Force to get him moving is 198 N. Force = ma = U(static)Mg

combining the 2 equations you get 198N = U(static)* 55kg *9.8m/s^2 Solve for U(static)

Same equation to keep him moving except with the dynamic force and the dynamic U

175N= U(kinetic)*55kg*9.8m/s^2 Solve (U dynamic)

You might be interested in

At what temperature the semiconductor behaves like conductor?

hammer [34]

Answer:

A semiconductor acts like an ideal insulator at absolute zero temperature that is at zero kelvin. It is because the free electrons in the valence band of semiconductors will not carry enough thermal energy to overcome the forbidden energy gap at absolute zero.

5 0

3 years ago

2000, the Millennium Bridge, a new footbridge over the River Thames in London, England, was opened to the public. However, after

sweet [91]

Answer:

n = 1810

A = 25 mm

Explanation:

Given:

Lateral force amplitude, F = 25 N

Frequency, f = 1 Hz

mass of the bridge, m = 2000 kg/m

Span, L = 144 m

Amplitude of the oscillation, A = 75 mm = 0.075 m

time, t = 6T

now,

Amplitude as a function of time is given as:

$A(t)=A_oe^{\frac{-bt}{2m}}$

or amplitude for unforce oscillation

$\frac{A_o}{e}=A_oe^{\frac{-b(6T)}{2m}}$

$\frac{6bt}{2m}=1$

$b=\frac{m}{3T}$

Now, provided in the question Amplitude of the driven oscillation

$A=\frac{F_{max}}{\sqrt{(k-m\omega_d^2)+(b\omega_d^2)}}$

the value of the maximum amplitude is obtained $(k=m\omega_d^2)$

thus,

$A=\frac{F_{max}}{(b\omega_d}$

Now, for n people on the bridge

Fmax = nF

thus,

max amplitude

$0.075=\frac{nF}{((\frac{m}{3T})2\pi}$

n = 1810

hence, there were 1810 people on the bridge

b) $A=\frac{F_{max}}{(b\omega_d}$

since the effect of damping in the millenium bridge is 3 times

thus,

b=3b

therefore,

$A=\frac{F_{max}}{(3b\omega_d}$

$A=\frac{1}{(3}A_o$

$A=\frac{1}{(3}0.075$

A = 0.025 m = 25 mm

6 0

3 years ago

Một thang máy chuyển động thẳng đứng hướng xuống dưới chậm dần đều với gia tốc a= -4m/s2. Trần thang máy treo một vật nhỏ bằng m

Free_Kalibri [48]

Answer:

ejkshdkashalsflasfaksg

7 0

3 years ago

A uniform solid cylindrical log begins rolling without slipping down a ramp that rises 28.0° above the horizontal. After it has

Novay_Z [31]

Answer:

3.07 m/s

Explanation:

6 0

3 years ago

How is work affected when an object is lifted straight up instead of using a ramp? Work will increase.

kifflom [539]

Without friction, the amount of work only depends on the final height,
and is not affected by the route used to get there.

If the ramp has no friction, then it has no effect on the total amount
of work done. The work to lift the load straight up is the same.

If the ramp has some friction, then it takes more work to use the ramp
than to lift the load straight up. Then the work to lift the load straight up
would be less than when the ramp is used.

3 0

3 years ago