Formulas Just incase you need Fnet = ma ; Force(net) = mass x acceleration

F(g) = Force of gravity = mass x gravity = mg = weight
(g=9.8m/s2)
Ff = μkFN
Friction Force = coefficient of sliding (kinetic) friction x Force (normal)

Ff = μsFN
Friction Force = coefficient of static (not moving) friction x Force (normal)

1. If your mass is 120 Kg how many Newtons do you weigh on the moon? (gravity on moon is 1.63m/s2)

2. A 40 kg mass is pulled along a surface by a horizontal force of 300N. Friction on the mass is 30N. What is the acceleration of the mass?

3. A 24kg box initially at rest on a horizontal floor requires a 75N force to set it in motion. What is the coefficient of static friction between the box and the floor?

4. A 40kg mass is pulled by a horizontal force of 200N, with at a constant velocity. What is μk?

5. If the coefficient of friction between a 50kg box and the floor is 0.30, what horizontal force is required to move the box at a constant speed across the floor?

6. A drag race car engine produces a force of 50,000N. Air friction on the car is 5,000N. How long will it take the car to reach 50m/s?

7. A 300lb motorcycle travels at 60ft/s, locks the brakes and slides to a stop with μk = 0.5, what is the kinetic friction force?

8. If the motorcycle in problem 9 takes three seconds to stop, what distance did it take to stop?

answer: 0.20

explanation: this can only be the answew because all the other measuremnets are not close

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles