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dedylja [7]
3 years ago
5

Calculate the force needed to bring a 950-kg car to rest from a speed of 90.0 km/h in a distance of 120 m (a fairly typical dist

ance for a non-panic stop). (b) Suppose instead the car hits a concrete abutment at full speed and is brought to a stop in 2.00 m.
Physics
1 answer:
WINSTONCH [101]3 years ago
6 0

Answer:

a)

2474 N

b)

148438 N

Explanation:

(a)

v₀ = initial velocity of the car = 90 km/h = 25 m/s

v = final velocity of the car = 0 m/s

d = stopping distance for the car = 120 m

F = force needed to bring the car to rest

m = mass of the car = 950 kg

Using Work-change in kinetic energy theorem

F d Cos180 = (0.5) m (v² - v₀²)

F (120) (-1) = (0.5) (950) (0² - 25²)

F = 2474 N

b)

v₀ = initial velocity of the car = 90 km/h = 25 m/s

v = final velocity of the car = 0 m/s

d = stopping distance for the car = 2 m

F = force needed to bring the car to rest

m = mass of the car = 950 kg

Using Work-change in kinetic energy theorem

F d Cos180 = (0.5) m (v² - v₀²)

F (2) (-1) = (0.5) (950) (0² - 25²)

F = 148438 N

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Answer:

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Explanation:

First, look at the picture to understand the problem before to solve it.

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J= \frac {-I_{c}}{\pi(c^{2}-b^{2}  ) }}

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B=\frac{6.68\times10^{-5}}{8.14\times10^{-5}} =0.820 T

c. d3=7.4 mm

Here, the point is located out of the cilinder. Therefore, we have to consider both, the conductor's current and the wire's current as follows:

B=\frac{u_{0}(I_w-I_c)}{2\pi d_3 } =\frac{2.011\times10^-5}{3.441\times10^{-4}} =0.0584 T

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