Question

a dog jumps onto a toy at a 45° angle. At the top of the dog's motion is the speed zero? and is the acceleration zero?

Answer 1

Ans : Speed = 0 , Acceleration g = 9.8 m/s² , in downward direction.

Explanation:

The dog jumps with an initial velocity and and as it moves upward it's velocity decreases and at highest point of it's trajectory , i.e. when it reaches the maximum hight , the velocity will be zero and then it will fall from highest point and speed increases. So at the top of the dog's motion , the speed is zero.

Now at the top , the speed is zero.i.e the dog stops for a moment and at that point , there will the acceleration due to gravity which will act on the dog in downward direction. But horizontal acceleration is zero.

So , at the top of the dog's motion , acceleration will not be zero but it will be g = 9.8 m/s².