Answer:
4.1 N
Step-by-step explanation:
We can solve this problem by using considerations about energy.
At the moment the stone is dropped, it has only gravitational potential energy:
where
is the weight of the stone
h = 10 m is the initial height of the stone
As the stone falls, part of this energy is converted into kinetic energy, while part into thermal energy due to the presence of the air friction, acting opposite to the motion of the stone:
where:
is the mass
v = 13 m/s is the final speed of the stone
is the thermal energy
The thermal energy is actually equal to the work done by the air friction on the stone:
where
F is the average force of friction
h = 10 m
Since the total energy must be conserved, we can combine the three equations, so we find:
And solving for F, we find the average force of air friction:
-5 ≤ 3m + 1 < 4
- 1 - 1 - 1
-6 ≤ 3m < 3
3 3 3
-2 ≤ m < 1
Solution Set: {m|-2 ≤ m < 1}, {m|m ≥ -2 and m < 1}, [-2, 1)
The answer is A.
There is not enough information to determine whether the pentagons are congruent.
Amy: x skirts
Betty: 2x skirts
Carol: (2x) + 7 skirts
If Amy has 18 less than Carol, than Carol's equation minus 18 equals Amy's equation:
[(2x) + 7] - 18 = x
+18 +18
(2x) + 7 = x + 18
- 7 -7
2x = x + 11
-x -x
x = 11
Input the solution for x into the girls equation to double check.
Amy: 11
Betty: 2(x)
2(11)
=22
Carol: (2x) + 7
22 + 7
=29
Does Amy have 18 less than Carol?
Carol - Amy = 18
29 - 11 = 18
18 = 18
the problem is solved