During spring tide, the sun, earth, and moon are in a straight line. This causes...............

Starting from rest, an elevator accelerates uniformly between the 1st and 2nd floors, and decelerates uniformly between the 5th

hichkok12 [17]

Answer:

The minimum scale reading during the trip was 560N.

Explanation:

So, in order to solve this problem, we must first prepare a drawing that will represent the situation. (See picture attached)

In the drawing we have the three situations represented. When the elevator goes up, when it travels at a constant velocity and when it decelerates.

We can now do an analysis of each of the situations:

When elevator starts moving:

When the elevator starts moving, it will be accelerated upwards, so the sum of forces will be equal to the mass times the acceleration. In this case, we have two forces, Weight and the normal force, which is the force the floor of the elevator is making upon the scale. This is the reading the scale will give you.

ΣF=ma

-W+N=ma

N=ma+W

As you may see, in this case the weight is added to the force applied by the elevator to accelerate, so the scale reading will be maximum here.

When the elevator has constant velocity:

If the elevator has constant velocity, then its acceleration will be zero, so the sum of the forces will be equal to zero.

ΣF=0

-W+N=0

N=W

On this stage, the scale will return a reading of 800N, since it will not be accelerated.

When the elevator is decelerating:

On the final stage of the trip, the elevator will have a negative acceleration (it is decelerating) so the sum of the forces will be equal to the product between the mass and the acceleration, so we get:

ΣF=-ma

-W+N=-ma

N=W-ma

In this final stage, we can see that the elevator's force is being subtracted from the weight due to the loss of velocity. This is where the scale will give you a minimum reading, so we analyze this stage.

Weight is found by multiplying mass and the acceleration of gravity:

W=mg

so we can rewrite our equation as:

N=mg-ma

when factoring the mass we get:

N=m(g-a)

the mass can be found by dividing the weight into the acceleration of gravity:

W=mg

$m=\frac{W}{g}$

$m=\frac{800N}{10\frac{m}{s^{2}}}$

m=80kg

we know that in the middle of the trip, the elevator will travel 6m in 1s, so the constant velocity is:

$V=\frac{d}{t}$

$V=\frac{6m}{1s}$

$V=6\frac{m}{s}$

this is the initial velocity for the final stage. The acceleration of the final stage can be found with the following formula:

$a=\frac{V_{f}^{2}-V_{0}^{2}}{2x}$

the final velocity is zero since it goes to a stop, so the formula becomes:

$a=\frac{-V_{0}^{2}}{2x}$

when substituting we get:

$a=\frac{-(6m/s)^{2}}{2(6m)}$

$a=-3\frac{m}{s^{2}}$

When substituting values we can now find the scale's reading:

$N=80kg(10m/s^{2}-3m/s^{2})$

$N=80kg(7m/s^{2})$

N=560N

So the minimum scale reading during the trip was 560N

6 0

3 years ago

A car traveling with constant speed travels 150 km in 7200s what is the speed of the car

Oksana_A [137]

Velocity is distance/time

so 150/7200=.0208km/s

unless you have to convert it to miles or something else. but use the formula!

5 0

3 years ago

5. Identify the reactants in this chemical equation:<br> 2H3PO4 → HAP20, +H2O

mixas84 [53]

Answer:

H=Hydrogen, PO4=Phosphate

Explanation:

Reactions are on the left side of arrow and products are on the right side of arrow.

4 0

3 years ago

A 19 kg solid disk of radius0.44 m is rotated about an

Vlad1618 [11]

Answer:

0.915 Nm

Explanation:

1 revolution = 2π rad

We can use the following equation of motion to find out the acceleration acting on the disk

$\omega^2 - \omega_0^2 = 2\alpha\Delta \theta$

where $\omega v = 2.5 rad/s is the final angular velocity of the disk, [tex]\omega_0$ = 0 rad/s is the initial velocity of the can when it starts from rest, $\Delta \theta$ is the angular distance traveled, $\alpha$ is the angular acceleration of the disk, which we care looking for: