What is the average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge?

 Average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge = 19.6 m/s

Explanation:

We have equation of motion , , s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

In this case the initial velocity of body = 0 m/s, acceleration = 9.8 , we need to calculate displacement when t = 4 seconds.

Substituting

So a distance of 78.4 meter has been traveled by pebble in 4 seconds.

Average speed = 78.4/4 = 19.6 m/s

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explanation:

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.