At First, there is chemical Energy( in your muscels) which is Used to Push down the spring. This Energy becomes the Energy of the spring, which increases until you stop pushing. If you Put your hand away, the Energy of the spring will become kinetic energ. This Energy is at the highest Level the Moment the book ist Leaving the spring. Afterwards, the kinetic Energy decreases while the Gravitational Potential Energy increases.
It’s 1 that would be the lowest point potential energy
First find the time it takes to hit the sand t
using s=1/2 g t^2
t^2= 8/9.8= 0.82 seconds
This means the sand was s = 8 * 0.82 = 6.5m away
The horizontal speed stays constant at 8 m/s
The vertical speed =.82 * 9.8 = 8.0 m/s
As the two velocities are equal the angle must be 45 degrees to the horizontal
Answer:
30N is the correct answer
