Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
Physics Work constant force?
A 1200kg car coasts on a horizontal road with a speed of 20m/s. After crossing a sandy stretch of the road 30.0m long its speed decreases to 17m/s.
(a) how much work is done on the car?
(b) find the magnitude of the average force on the car
Do you use the 1/2 mv*2 formula and subtract to find work? I'm beginning this chapter in physics and don't understand this problem fully.
Ok, so I used the 1/2mv*2 formula and got
1/2 (1200)(20*2) - 1/2 (1200)(17*2) = 66,600 J
Then used the V*2 = Vi*2 + 2(a)d and got 17*2 = 20*2 + 2a(30)
a = (-1.85)m/s*2
F = ma
F = (1200)(1.85)
F = 2220 N
positive since its magnitude? or should it be negative?
1 Answer
- 1 decade agoFavorite Answer
yes you do what you said, because energy is conserved. also, for b you use the formula Vf^2=Vi^2+2ad and get the acceleration. then F=ma. you have ur mass and theres ur acceleration.
