39. A dog runs on a waxed floor at an initial speed of 2 m/s. It slides to a stop with an acceleration of -0.43 m/s2. How long does it take for the dog to stop?

Explanation:

Use the one-dimensional equation

where vf is the final velocity of the dog, v0 is the initial velocity of the dog, a is the acceleration of the dog, and t is the time it takesto reach that final velocity. For us:

0 = 2 + -.43t and

-2 = -.43t so

t = 4.7 seconds

i think it because equal matrices have equal dimensions, only square matrices can be symmetric. for all indices and . every square diagonal matrix is symmetric, since all off-diagonal elements are zero. in linear algebra, a real symmetric matrix represents a self-adjoint operator over a real inner product space.