Mathematics, 26.09.2019 18:30, nyameneak

Afactory worker pushes a 30.0 kg crate a distance of 4.3 m along a level floor at constant velocity by pushing downward at an angle of 30∘ below the horizontal. the coefficient of kinetic friction between the crate and floor is 0.25.

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answered: victoriabrooks5766

a) the worker must apply 73.5 Newtons

b) work done = 330.75 Joules

c) work done = -330.75 Joules

Work done by normal force = 0 Joules

Work done by gravity = 0 Joules

e) total work done = 0 joules

Step-by-step explanation:

The complete question:

"A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on it. The coefficient of kinetic friction between the crate and the floor is 0.25. (a) What magnitude of force must the worker apply? (b) How much work is done on the crate by this force? (c) How much work is done on the crate by friction? (d) How much work is done on the crate by the normal force? By gravity? (e) What is the total work done on the crate?"

distance, s = 4.3

mass, m = 30

Coefficient of friction, $\mu_k=0.25$

The worker here must apply a force, $F_{worker}$ equal to kinetic frictional force F_k .

We know $F_k=\mu_k mg$

We know g = 9.8, thus plugging in we get:

$F_{worker}=F_k=\mu_k mg=0.25*30*9.8=73.5$

Thus, the worker must apply 73.5 Newtons

Work is given by the formula:

$W=F_{worker} s Cos\phi$

F and s are in the same direction, so angle ( $\phi$ ) is 0

Now we find work done:

$W=F_{worker} s Cos\phi\\W=73.5*4.5*Cos(0)\\W=73.5*4.5\\W=330.75$

Hence, work done = 330.75 Joules

We use same formula but remember that the angle is 180 degrees since frictional force is acting against it (opposite).

Thus we have:

$W=F_{worker} s Cos\phi\\W=73.5*4.5* Cos(180)\\W=-330.75$

Hence, work done = -330.75 Joules

Work on by normal force would be perpendicular, so angle would be 90 degrees. THus

$W_n=F_{worker} s Cos (90)\\W_n=0$

Work by gravity would be opposite of that direction. That would be -90 degrees. Thus

$W_g=F_{worker} s Cos(-90)\\W_g=0$

Thus

Work done by normal force = 0 Joules

Work done by gravity = 0 Joules

Net work done on crate will be sum of all individual work done.

$W_{net}=W{worker}+W_k+W_n+W_g$

Plugging in the values, we have:

$W_{net}=W{worker}+W_k+W_n+W_g\\W_{net}=330.75-330.75+0+0=0$

Hence

total work done = 0 joules

Note: this is 0 because F_worker and F_k are working opposite to each other

answered: Guest

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2

answered: Guest

you forgot the options, but i found them anyways, the correct answer is "john wilson believes that words and actions based on the intellect are superior to those based on emotions".

john wilson is depicted as an extremely intelligent man. the point of the excerpt is to make a sort of distinction between emotional and rational intelligence. he happens to have both attributes, but he clearly favors his intellectual gifts. at the same time, because of his religious background, he's a little bit conflicted with this and it makes him ashamed.

hope this !