help with physics please.?

Three forces act on the sled.

1 ) Weight of Mr. Doyle and sled, mg acting downwards,

2 ) Normal reaction, N, from the surface perpendicular to it and

3) Frictional force, μN, opposite to the direction of motion.

These forces can be resolved into two components, one along the direction of motion and the other perpendicular to it.

Perpendicular components balance each other as there is no motion in that direction.

=> mg cos 19° = N

In the direction of motion, net force

mg sin 19° - μN = ma, where a = acceleration of Mr. Doyle and sled.

Plugging the value of N from the previous equation,

mg sin 19° - μmg cos 19° = ma

=> a

= g (sin19° - μcos19°)

= (9.8) * [ 0.3256 - (0.18) * (0.9455) ] m/s^2

= 1.522 m/s^2.

Acceleration=coefficient of kinetic friction times the normal force.

I think.

does it give a mass for mr. doyle and the sled?

a = F/m

F = component of weight down the ramp - friction

F = m g sin19 - m g (0.18) cos19

a = F/m = g[sin19 - 0.18*cos19]

masses are irrelevant. normal force = mass * acceleration = same mass * accel-gravity cos(theta). divide the mass and you get normal force accel = grav cos(theta).

you know that kinetic friction force = kinetic coefficient * normal force = k * mass * grav cos(theta). calculate accordingly

units please for the 0.18 CKF, and the mass of Mr. Doyle.

a = Fnet/m

Fnet = m*g*sinΘ - µ*m*g*cosΘ

Ergo,

a = (gsinΘ - µgcosΘ) = 9.8*sin19° - .18*9.8*cos19° = 1.52 m/s²

N.B.: µ is dimensionless

I really have no idea