Answer:

Explanation:
m = Mass of object = 
mg = Weight of object = 20 N
g = Acceleration due to gravity = 
v = Final velocity = 15 m/s
u = Initial velocity = 0
d = Distance moved by the object = 150 m
= Angle of slope = 
f = Force of friction
fd = Work done against friction
The force balance of the system is

The work done against friction is
.
The mineral with Mohs hardness would be scratched because the mineral with Mohs 7 hardness is stronger than the Mohs 5 mineral. Eventually, that mineral would turn into dust if you kept rubbing it.
The hardest part of the job is to find the right formula to use, and write it down. You've already done that ! The rest is just turning the crank until an answer falls out.
You wrote. E = m g h.
Beautiful.
Now divide each side by (g h), and you'll have the formula for mass:
m = E / (g h).
You know all the numbers on the right side. Just pluggum in, do the arithmetic, and you'll have the mass.
0.04m²
Explanation:
Given parameters:
Pressure = 250000Pa
Weight = 40000N
Unknown:
Area of each foot = ?
Solution:
Pressure is the force exerted per unit area of a body
Pressure = 
To find the area;
Area = 
Area =
= 0.16m²
The force exerted by all the four feet is 0.16m²
the area of each feet =
= 0.04m²
Learn more:
Pressure brainly.com/question/7139767
#learnwithBrainly