Reachs a speed of 7.0m/s^2 at the bottom of the hill
Coefficient of kinetic friction between sled + girl and hard icy snow 0.050, the total weight of the sled + girl = 645N.
2006-10-25 23:30:59 · 4 answers · asked by lauren u 1 in Science & Mathematics ➔ Physics
This problem is about kinetic energy, work energy, kinetic friction, and conservation of energy.
KE=1/2mv^2, where KE is the kinetic energy in J, m the mass in kg, and v the speed in m/s. m=w/g =645/9.8
Substitute known values:
KE=1/2*[645/9.8]*7^2
=1612.3 J
force of kinetic friction, f=uR where f is in N, u the coefficient of kinetic friction of 0.050, and R the force normal to the hard icy snow of 645N.
Substitute known values:
f=0.050*645
=32.25N
Work = f*s, where f is the force of kinetic friction, and s the displacement in meters.
Substitute known values:
Work =32.25s
Based on the principle of conservation of energy:
KE=Work
1612.3=32.25s
s=1612.3/32.25
=50 meters
2006-10-27 03:12:34 · answer #1 · answered by tul b 3 · 0⤊ 0⤋
The total friction force acting is -645*0.050=-32.25 N
the actual mass is calculated by mg=645=>m=64.5 k"g
the deceleration of the sled is
F=ma=> -32.25=64.5a => a=-0.5 m/s^2
after a time t the sled will have 0 velocity: v=v0+at=7-0.5t=0
t=7/0.5=14 s
after a time t the sled would have moved by x:
x=v0*t+a*t^2/2=7*14-0.5*14^2/2
=98-49=49 meters
2006-10-25 23:38:56 · answer #2 · answered by mashkas 3 · 0⤊ 0⤋
you calculate the friction as being equal to Coefficient * Weight, which gives you the opposing force, which gives you the negative acceleration (deceleration) as being equal to Force / Mass, which you can use in the formula for the law of trajectory (don't know English terminology), which gives you total distance traveled, considering initial speed as given.
hope is correct. the formula for trajectory law should be in your physics book
2006-10-25 23:47:31 · answer #3 · answered by ╠╬╣ 3 · 0⤊ 0⤋
3 m ok
2006-10-25 23:35:33 · answer #4 · answered by DAVID M 3 · 0⤊ 0⤋