6. a physics book slides off a horizontal table top with a speed of 1.25m/s. it strikes a floor in 0.4s.
what's the speed with which the book strikes the floor?

4.11 m/s

Explanation:

Given:

v₀ₓ = 1.25 m/s

aₓ = 0 m/s²

v₀ᵧ = 0 m/s

aᵧ = -9.8 m/s²

t = 0.4 s

Find: v

First, in the x direction:

vₓ = aₓt + v₀ₓ

vₓ = (0 m/s²) (0.4 s) + 1.25 m/s

vₓ = 1.25 m/s

And in the y direction:

vᵧ = aᵧt + v₀ᵧ

vᵧ = (-9.8 m/s²) (0.4 s) + 0 m/s

vᵧ = -3.92 m/s

The net speed is found with Pythagorean theorem:

v² = vₓ² + vᵧ²

v² = (1.25 m/s)² + (-3.92 m/s)²

v = 4.11 m/s

the moon affects the earth gravitation ally, causing certain motions of that body and also producing tides in its ocean and atmosphere. the tidal wave in our atmosphere is, however, far too minute to be an effective cause in any known meteorological phenomenon.

explanation: