A92-kg skier is sliding down a ski slope that makes an angle of 40 degrees above the horizontal direction. the coefficient of kinetic friction between the skis and the snow is 0.293. neglecting any air resistance, what is the acceleration of the skier?
a) 5.8 m/s2
b) 4.9 m/s2
c) 9.8 m/s2
d) 4.1 m/s2
e) 2 m/s2

d) a = 4.1 m/s²

Explanation:

m = 92 Kg

∅ = 40º

μ = 0.293

a = ?

We can obtain the forces in the direction x' (of motion)

Wx' = W*Sin ∅ = m*g*Sin ∅

Ffriction = μ*N = μ*m*g*Cos ∅

then we use Newton's 2nd Law as follows:

Wx' - Ffriction = m*a

m*g*Sin ∅ - μ*m*g*Cos ∅ = m*a

⇒   a = g*(Sin ∅ - μ*Cos ∅)

⇒   a = (9.81 m/s²)*(Sin 40º - 0.293*Cos 40º)

⇒   a = 4.1038 m/s²

we need to know the time interval during which the force acts. impulse of force = momentum change

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me