Answer:
E) The net work done by the two forces is zero joules.
Explanation:
As the elevator is moving at a constant speed, it is the same as being stationary. The tension in the cable perfectly balances the gravitational force. Work done by gravity = mgh
Work done by the tension = -Th
where, T = tension force. The negative sign comes as the direction of T is opposite to the direction of g. As the elevator moves at a constant speed, the magnitude of the two forces must be equal. Therefore, the total work done,
W = (mg - T)h = 0
Answer:
3.33 seconds
Explanation:
We can use the velocity formula [ v = u + at ] to solve.
Find the value "u".
135km/h -> 135km*1000m/3600s -> 37.5m/s
Find the value "v".
75km/h -> 75km*1000m/3600s -> 20.83m/s
Keep in mind we are dealing with "deceleration" so when we input 5.0m/s into the formula, it will be a negative value.
Now, find "t" which is the value we aren't given with the values we're given in the question.
20.83 = 37.5 - 5t
-16.67 = -5t
3.33 = t
Best of luck!
Answer:
K = G Mm / 9R
Explanation:
Expression for escape velocity V_e = 
Kinetic energy at the surface = 1/2 m V_e ²
= 1/2 x m x 2GM/R
GMm/R
Potential energy at the surface
= - GMm/R
Total energy = 0
At height 9R ( 8R from the surface )
potential energy
= - G Mm / 9R
Kinetic energy = K
Total energy will be zero according to law of conservation of mechanical energy
so
K - G Mm / 9R = 0
K = G Mm / 9R
MgCl2 is ionic compound.........Mg +2 and Cl -1
both charges are cross multiplied to each element......formula tells us that to balance the positive and negative charges on both sides they are cross multiplied........MgCl2......meaning there is one atom of Mg and 2 atoms of Cl.......
HOPE IT HELPS !!!
