Answer:
Buoyancy force and surface tension are the reactions that take places between soap and pepper experiment.
Explanation:
Surface tension:
The surface tension of a liquid is the tendency of liquid surfaces to resist an external force due to the cohesive nature of its molecules.
The pepper and soap experiment helps you to understand buoyancy force and surface tension.
Reaction between the pepper and soap is as following.
- The pepper flakes float because of buoyancy force. It makes the pepper flakes to move away to the edge of the plate.
- This happens because the liquid dish soap changes the surface tension of water.
- And The pepper flakes are so light, it floats on the water surface due to surface tension.
- when we add soap, it breaks the surface tension of water, but the water resists it. So they pull away from the soap along with the pepper flakes.
- This pushes the pepper away from your soap covered finger.
This is the reaction that take places between soap and pepper experiment.
Learn more about Pepper and soap experiment here:
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W=20 e(-kt)
A. Rearranging gives k= -(ln(w/20)/t
Substituting w= 10 and solving gives k=0.014
B. Using W=20e(-kt). After 0 hours, W=20. After 24 hours, W=14.29g. After 1 week (24x7=168h) W=1.9g
C. Rearranging gives t=-(ln(10/20)/k. Substituting w=1 and solving gives t=214 hours.
D. Differentiating gives dW/ dt = -20ke(-kt). Solving for t=100 gives dW/dt = 0.07g/h. Solving for t=1000 gives 0.0000002g/h
E. dW/dt = -20ke(-kt). But W=20e(-kt) so dW/dt = -kW
Answer:

Explanation:
The ball will rise decreasing its speed until it reaches the highest point where its speed will be zero. From this point the tennis ball will begin to fall again, in the free fall the tennis ball will gain speed but now in the opposite direction. When it returns to the same point where it was launched, its speed will be the same as the one that was launched but with the opposite sign.

We can check this using the equation:

where 
ang h is the height, but because the ball returns to the same point where it started, h =0
then


the initial and final velocity will be the same in number, but we know that the ball is going in the opposite direction, so the final velocity must have the opposite sign from the initial velocity
so if
,
