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? asked in Science & MathematicsPhysics · 6 years ago

Physics help!?

A truck is traveling due west at 30.4 km/h through a rain storm. The wind blows directly east so that the rain comes down making an angle of 10.0° with respect to the vertical. The rain traces on the side windows of the truck make an angle of 54.0° with the vertical (angled toward the rear of the truck). Determine the following.

a) speed of the rain with respect to the Earth

b) speed of the rain with respect to the truck

1 Answer

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  • NCS
    Lv 7
    6 years ago
    Favorite Answer

    Vrain w/r/t earth = Vrain w/r/t truck + Vtruck w/r/t earth

    Vr/e*sin10 i + Vr/e*cos10 j = Vr/t*sin54 i + Vr/t*cos54 j - 30.4km/h i + 0 j

    Now let's look just at the east-west ("x," or "i") components:

    Vr/e*sin10 = Vr/t*sin54 - 30.4km/h

    and now just the north-south ("y," or "j") components:

    Vr/e*cos10 = Vr/t*cos54

    Then Vr/e = Vr/t * 0.6 → plug this into the horizontal equation

    Vr/t * 0.6 * sin10 = Vr/t * sin54 - 30.4km/h

    Vr/t = 30.4km/h / 0.705 = 43 km/h ◄ (b) speed of rain w/r/t truck

    Vr/e = Vr/t * 0.6 = 25.9 km/h ◄ (a) speed of rain w/r/t Earth

    Hope this helps!

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