# Physics Kinematics

#### Maverick56

##### Full Member
A car is moving at 40mph. If the mass of the car is 2,300 kg and the coefficient of kinetic friction is 0.4, what is the stopping distance in ft?

7+ Year Member

#### Ibn Alnafis MD

##### Full Member
10+ Year Member
A car is moving at 40mph. If the mass of the car is 2,300 kg and the coefficient of kinetic friction is 0.4, what is the stopping distance in ft?

First convert 40mph to m/s
KE = Fn * d
1/2 mv^2 = 0.4mg * d
(v^2)/(2 *0.4*g) = d (in meters, so multiply by 3 to get ft)

#### BerkReviewTeach

##### Company Rep & Bad Singer
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10+ Year Member
First convert 40mph to m/s
KE = Fn * d
1/2 mv^2 = 0.4mg * d
(v^2)/(2 *0.4*g) = d (in meters, so multiply by 3 to get ft)

Spot on solution, although I came up with a slightly larger final number (in the 140 m +/- range). It comes down to our rounding differences I suspect. In a multiple choice scenario, all three answers so far will likely lead to the best answer of the four choices.

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