Answer:
893 Newtons
Explanation:
m = Mass of Usain Bolt = 94 kg
a = Acceleration of Usain Bolt in the first 0.89 seconds = 9.5 m/s²
From Newton's Second law
Force



The average horizontal force exerted by Bolt against the ground during the first 0.890 s of the race is 893 Newtons
Answer:
The magnetic field at a distance x = 5 m is 1.59 nT
Explanation:
Length of the wire, L = 2 cm = 0.02 m
Current, I = 20 A
x = 5 m
Magnetic field at a distance x = 5 m due to an infinitely long wire is given by:


Explanation:
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Answer:
μ₁ = 0.1048
μ₂ = 0.1375
Explanation:
Using static equation can find in both point the moment and the forces so:
∑ M = F *d , ∑ F = 0
∑ M A = 0
N₁ * 3 - 200 * 9.81 * 1.5 = 0
N₁ = 981
∑ M y = 0
N₂ + 300 * ³/₅ - 981 - 20 * 9.81 = 0
N₂ = 997.2 N
∑ M C = 0
F₁ * 1.75 - 300 * ⁴/₅ * 0.75 = 0
F₁ = 102.86
∑ M B = 0
300 * ⁴/₅ * 1 - F₂ * 1.75 = 0
F₂ = 137.14 N
The Force F1 and F2 related the coefficients of static friction
F₁ = μ₁ * N₁ ⇒ 102.86 N = μ₁ * 981 ⇒ μ₁ = 0.1048
F₂= μ₂ * N₂ ⇒ 137.14 N = μ₂ * 997 ⇒ μ₂ = 0.1375
Newton's second law also helps to explain what happens every time an athlete lands during running. When the foot hits the track, it will decelerate to a stop before leaving the track again. The faster the deceleration, the greater the force of impact on the foot.