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a 4.23 kg ball travels at 2.79 m/s across level ground against friction, where the coefficient of kinetic friction is equal to 0.156. How long does the ball travel for before coming to a complete stop?

Respuesta :

Answer:

2.55 m

Explanation:

Assuming the ball slides without rolling, there are two methods that can be used to find the displacement of the ball. Method 1 is to use the work-energy theorem, which says the work done on the ball is equal to the change in kinetic energy. Method 2 is to use Newton's second law of motion, which says the net force on an object is equal to its mass times acceleration, then use kinematics to solve for displacement.

Method 1: Work-energy theorem

W = ΔKE

Fd = KE − KE₀

-mgμ d = 0 − ½ mv₀²

gμ d = ½ v₀²

d = ½ v₀² / (gμ)

d = ½ (2.79 m/s)² / (9.8 m/s² × 0.156)

d = 2.55 m

Method 2: Newton's second law and kinematics

F = ma

-mgμ = ma

a = -gμ

a = -(9.8 m/s²) (0.156)

a = -1.53 m/s²

Given:

u = 2.79 m/s

v = 0 m/s

a = -1.53 m/s²

Find: s

v² = u² + 2as

(0 m/s)² = (2.79 m/s)² + 2 (-1.53 m/s²) s

s = 2.55 m