- #1
Jessica Sweet
- 10
- 0
Please help! I have a test tomorrow.
1. Homework Statement
A car with a weight of 15,000 N moves horizontally at 30 m/s.
a) What is the car's KE?
b) What will be the magnitude friction force to stop the car over a 60m distance?
F=ma
KE=1/2*m*v2
a) mass of car = 1531 kg
KE = 1/2(1531)(30)2 = 690,000 J
b) This is where I hit trouble.
I found acceleration by (0-30)/2 = -15 m/s2
Then I used F=ma, so Ff = (1531)(-15) = -22,965 N
Not the correct answer...
1. Homework Statement
A car with a weight of 15,000 N moves horizontally at 30 m/s.
a) What is the car's KE?
b) What will be the magnitude friction force to stop the car over a 60m distance?
Homework Equations
F=ma
KE=1/2*m*v2
The Attempt at a Solution
a) mass of car = 1531 kg
KE = 1/2(1531)(30)2 = 690,000 J
b) This is where I hit trouble.
I found acceleration by (0-30)/2 = -15 m/s2
Then I used F=ma, so Ff = (1531)(-15) = -22,965 N
Not the correct answer...
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