Calculate how fast the car was travelling when brakes were applied

[chwala]

Homework Statement

see attached.

Relevant Equations

Mechanics

My query is on highlighted.


This was straightforward. I thought that coefficient of friction ought to lie between $0$ and $1$ maybe i need to check that again anyway;

$F_{lim} = 1.5 ×15000= 22, 500 N$

Using $v^2 = u^2 +2as$ and $F=ma$

$22,500 = 1500a$

$a = -15$

and using $v^2 = u^2 +2as$

$0 = u^2 + (2 ×-15×7)$

$u^2 = 210$

$u = 14.5 m/s$ correct to one decimal point.

 

[haruspex]

Homework Statement: see attached.
Relevant Equations: Mechanics

I thought that coefficient of friction ought to lie between 0 and 1

A common misunderstanding.