Police Lieutenant
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Police lieutenant’s son charged in beating outside Sanford bar
A police officer's son has been charged with beating a man outside a Seminole County bar.
police lieutenants?
Police lieutenants, examining the scene of an accident involving two cars, measure the skid marks of one of the cars, which nearly came to a stop before colliding, to be 76 m long. The coefficient of kinetic friction between rubber and the pavement is about 0.80. Estimate the initial speed of that car assuming a level road.
_____m/s
Ffrict = u*Fn
|Fn| = |W| = m*g
Ffrict = u*m*g
The work done by friction is given by Work_frict = Ffrict*d
Work_frict = u*m*g*d
Assuming all the energy before the collision was kinetic and and since it almost comes to a stop, at the time of the collision, all of that initial energy is transformed to heat from the work done by friction.
KE_i = 1/2*m*v^2
So, since KE_i = Work_frict,
1/2*m*v^2 = u*m*g*d
m is on both sides of the equation and can be cancelled out. Plug in the values and solve for v.