<h2>Ratio of final kinetic energy to initial kinetic energy is 16.</h2>
Explanation:
Kinetic energy , KE = 0.5mv²
Here car speeds up to four times the initial speed, we need to find ratio of final kinetic energy to initial kinetic energy.
Final speed = 4 x Initial speed = 4v
Initial KE = 0.5mv²
Final KE = 0.5 x m x (4v)²
Final KE = 16 x 0.5 x m x v²
Final KE = 16 x Initial KE
Ratio of final kinetic energy to initial kinetic energy is 16.
The speed of the spring when it is released is 3.5 m/s.
The given parameters:
- <em>Mass of the block, m = 2.5 kg</em>
- <em>Spring constant, k = 56 N/m</em>
- <em>Extension of the spring, x = 0.75 m</em>
The speed of the spring when it is released is calculated by applying the principle of conservation of energy as follows;

Thus, the speed of the spring when it is released is 3.5 m/s.
Learn more about conservation of energy here: brainly.com/question/166559
<span>The purpose of pumping is to increase overall velocity. The person drops down into a crouch while traversing the more-or-less flat bottom of the U-shaped pipe or bowl. Then, as he enters the sloped part of the ramp or bowl, called the transition, he straightens his legs and rises up. By raising his center of mass just at the beginning of the arc, the person gains energy and thereby increases his speed.</span>
Rate of change of momentum = impact force
(m*v-m*u)/t = F
4000*20/t = 80000 (note: v is zero as it stopped)
<span>soo, t = 1 sec</span>
Answer:197.504 N
Explanation:
Given
Two Charges with magnitude Q experience a force of 12.344 N
at distance r
and we know Electrostatic force is given



Now the magnitude of charge is 2Q and is at a distance of 

F'=16F
F'=197.504 N