Answer:
The runner's acceleration was 
Explanation:
<u>Constant Acceleration Motion</u>
It's a type of motion in which the velocity of an object changes by an equal amount in every equal period of time.
Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

Solving for a:

The runner speeds up from vo=5 m/s to vf=9 m/s in t=4 seconds, thus:


The runner's acceleration was 
The mine involves digging tunnels and shafts deep underground is the underground mining.
<h3>What is mining?</h3>
Mining is the digging of the Earth deep down in search of some precious elements or resources found on Earth.
Underground mining is the digging down into the earth in order to create tunnels. The shafts need to be inserted into those tunnels so that it reaches the deposits of resources.
Thus, underground mining involves digging tunnels and shafts deep underground.
Learn more about mining.
brainly.com/question/14277327
#SPJ4
Answer:

Explanation:
From the question we are told that
Mass 
Height 
Generally the equation for velocity before impact is is is mathematically given by



Generally the equation for Kinetic Energy is is mathematically given by




Potholder should have high insulation and low conductivity, therefore the correct answer is the option B
<h3>What is insulation?</h3>
Insulation is a type of material used to create barriers to the transmission of the form of energy which either is in form of heat or electricity.
For outdoor trips in cold weather, several thin layers act as better insulating barriers for heat transfer.
The ability of an electric charge or heat to pass through a material is measured by its conductivity. A material is considered a conductor if it offers very little resistance to the flow of thermal or electric energy.
Thus, Potholders should be highly insulated and have low conductivity, therefore the correct answer is the option B
Learn more about insulation from here
brainly.com/question/14363642
#SPJ1
your question seems incomplete, the complete question is
To be effective, a pot holder should have low _____. viscosity conductivity malleability density
Answer
4.8 N
If the box is moving with a constant velocity, then we can say that the system is in equilibrium. This is because if the external force (F->) was greater than other forces the box would be accelerating. This tells us that this force (F->) is just enough to overcome friction and so it must be equal to 4.8 N.
The normal force has no effect to the horizontal velocities or forces. It is equal to -Weight. That is -74 N. The negative sign shows that the force is in opposite direction.