Answer: D
Height of marble from ground
Explanation:
From the formula of kinetic energy and potential energy,
K.E = 1/2mv^2
While
P.E = mgh
From all the parameters given from the question. You can see that mass is constant, acceleration due to gravity is also constant.
Independent variable must be a value that can varies.
Since Jack rolled a marble down a ramp and recorded the potential energy and kinetic energy of the marble at different positions on the ramp to see the effects on both energies.
This different position must be the height which will produce an effect on the potential and kinetic energy of the marble.
Independent variable always provides an effect for dependent variable. Which are kinetic energy and potential energy in this case.
Height of marble from ground is the right answer.
The pressure exerted by the block on the table is given by:

where W is the weight of the box, and A is the bottom surface area of the box.
The weight of the box is: 
Substituting into the first equation, we find the pressure:

The components of the net force on the cart is determined as 67.66 N.
<h3>
Component of net force on the cart</h3>
The component of net force on the cart is determined by resolving the forces into x and y -components.
T1 = 30 N
T2 = 40 N
T1x = -30cos(0) = 30 N
T1y = 30sin(0) = 0
T2x = 40 x cos(30) = 34.64 N
T2y = 40 x sin(3) = 20 N
∑X = 30 N + 34.64 N = 64.64 N
∑Y = 0 + 20 N = 20 N
<h3>Resultant force</h3>
R = √(64.64² + 20²)
R = 67.66 N
Learn more about net force here: brainly.com/question/25239010
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Friction , as the angle gets huger and higher , this is less and less normal force into the inclined plane .