Answer:
(a) v = 1.71 m/s
(b) μ = 0.005
Explanation:
(a)
Using the law of conservation of the momentum:
where,
m₁ = mass of person = 61.1 kg
m₂ = mass of sled = 16.1 kg
u₁ = initial speed of the person = 2.16 m/s
u₂ = initial speed of the sled = 0 m/s
v₁ = v₂ = v = final speeds of both the person and the sled = ?
Therefore,
<u>v = 1.71 m/s</u>
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(b)
The kinetic energy lost by the sled must be equal to the frictional energy:
K.E = fd
where,
μ = coefficient of kinetic friction = ?
d = distance covered = 30 m
g = acceleration due to gravity = 9.81 m/s²
Therefore,
<u>μ = 0.005</u>
Answer:
b.) All these technologies use radio waves, including high-frequency microwaves
d.) Microwave ovens emit in the same frequency band as some wireless Internet devices.
e.) The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies listed above.
f.) All these technologies emit waves with a wavelength in the range of 0.10 to 10.0 m.
Explanation:
For option D. The frequency range of microwave ovens is 2450 MHz = 2.4 GHz, which intersects with wireless internet technology with range of 2.4 to 2.6 GHz.
For E, wavelenght and frequency are inversely proportional. Wireless internet service has the greatest frequency band and hence the shortest wavelenght band.
For F, in all these radiations, the highest Freq is 2.6 GHz and the lowest is 40 MHz. Wavelenght is speed of light (3x10^8 m/s) divided by the frequency.
2.6 GHz = 2.6x10^9 Hz
Wavelenght = 3x10^8 ÷ 2.6x10^9 = 0.1 m
40 MHz = 40x10^6
Wavelenght = 3x10^8 ÷ 40x10^6 = 7.5 m
Answer:
P max = 1000 pa
P min = 200 pa
Explanation:
P = F/A
pressure will be maximum when surface gets minimum. so to find the maximum amount of pressure we need to calculate the minimum surface. it is 2cm×5cm = 10cm² = 0.001m² . then we have:
P = 1 / 0.001 = 1000 pa
to find minimum pressure the surface that must be chosen is 10cm×5cm = 50cm² = 0.005m² .
P = 1 / 0.005 = 200 pa