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question 13 of 25
question 13
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a 975 - kg car accelerates from rest to 26.7 m/s in a distance of 120 m. what is the magnitude of the average net force acting on the car? (hint: find acceleration first, using equations of kinematics from chapter 2, then find the net force)
7900 n
91 n
740 n
1300 n
2900 n

Explanation:

Step1: Use kinematic - equation to find acceleration

We use the equation $v^{2}=v_{0}^{2}+2ax$. Given $v_{0} = 0$ (starts from rest), $v = 26.7$ m/s and $x=120$ m.
$a=\frac{v^{2}-v_{0}^{2}}{2x}=\frac{26.7^{2}-0^{2}}{2\times120}$
$a=\frac{712.89}{240}\approx2.97$ m/s²

Step2: Use Newton's second - law to find net force

Newton's second - law is $F = ma$. Given $m = 975$ kg and $a\approx2.97$ m/s².
$F=975\times2.97\approx975\times3 = 2925$ N (approximate for quick check). More precisely, $F=975\times2.97=2905.75\approx2900$ N

Answer:

2900 N