Two objects were lifted by a machine
1 answer:
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Answer:
Work done, W = 0 J
Explanation:
It is given that,
Mass of the bag, m = 7 kg
If a person carries a bag of groceries 1.2 m above the ground at constant speed across a 2.7 m room. We need to find the amount of work done on the bag he the process. It is given by :
Where
θ = angle between the force and the direction of motion. Here, θ = 90° (its weight is acting vertically downward and it is moving forward)
Since, cos(90) = 0
⇒ Work done, W = 0 J
So, the work done on the bag is zero. Hence, the correct option is (b) "0 J".
Answer:
We need a time of 8.118 minutes or higher in order to be sponsored by the company
Explanation:
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Let X the random variable that represent the running times of a population, and for this case we know the distribution for X is given by:
Where and
minutes.
And we want the fastest 5% of runners, so we need a value a such that:
or
We need on the right tail of the distribution a value a that gives to us 95% of the area below and 5% of the area above. Both conditions are equivalent.
Let's use the condition , the best way to solve this problem is using the z score with the following formula:
So we need a value from the normal standard distribution that accumulates 0.95 of the area on the left and 0.05 on the right. This value on this case is 1.64 and we can founded with the following code in excel:
"=NORM.INV(0.95,0,1)"
If we apply the z score formula to our case we have this:
So then based on the equalities we have this:
And if we solve for a we got:
So then we need a time of 8.118 minutes or higher in order to be sponsored by the company
Answer:
a) The weight of the motor is 1120 N
b) The distance of the center of gravity is 1.71 m
c) The weight of the motor is 920 N
d) The distance of the center of gravity is 1.79 m
Explanation:
a) The expression of the forces acting in the vertical direction is:
wmotor = F1 + F2
F1 = 410 N
F2 = 710 N
wmotor = 410 + 710 = 1120 N
b) The momentum of equilibrium about the center of the gravity is:
F1 * x = F2 * (l - x)
Clearing x:
c) The expression for the forces acting in the vertical direction is:
wboard + wmotor = F1 + F2
wmotor = F1 + F2 - wboard
wmotor = 410 + 710 - 200
wmotor = 920 N
d) The same that b)