Essai Bonus Poin

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No. 1) A truck of mass 2 tons moves from rest so that its speed is 20 m/s. The distance covered by the truck is 200m. How big is the truck? (200,000N)

No. 2) A motorcycle with a mass of 100 kg brakes suddenly because there is a speed bump so the speed of the motorcycle changes from 40m/s to 30m/s in 2 seconds. Calculate the magnitude of the braking force of the motorcycle? (500N)​

Essai Bonus Poin

Jawaban:

Penjelasan:

1) mass of the truck, m=2tons=2000kg

use g=10m/s^2, we get

w=2000kgtimes 10m/s^2=20000N

W=Ftimes (200m)=frac{1}{2}2000kg((20m/s)^2-(0m/s)^2)\\F=2000 N

2) the distance needed by the motorcycle from 40m/s to 30m/s is

s=v_0t+frac{1}{2}at^2=40m/s(2s)+frac{1}{2}(-5m/s^2)(2s)^2=80m-10m=70m

by using energy principle

W=Fs=frac{1}{2}m(v_2^2-v_1^2)

F=frac{50kg((40m/s)^2-(30m/s)^2)}{70m}=500N