All categories

3 years ago

Zach, whose mass is 80 kg, is in an elevator descending at

2 answers:

5 0

(a) apparent weight is actual weight = mg = (79)(9.81) = 775 N ANS (a) {reason: elevator is not accelerating therefore Z's net acceleration is "g"}
(b) elevator decelerates at 12/2.5 = -4.80 m/s this reduces net acceleration acting on Z to (9.81 - 4.80) = 5.01 m/s² while braking with 5.01 m/s² acting on Z, his apparent weight = (79)(5.01) = 396 N ANS (b)

goldfiish [28.3K]3 years ago

4 0

Answer:

a) W = 784 N

b) R = 1050.4 N

Explanation:

Given

Let us consider the upward direction positive

Mass of Zach m = 80 kg

initial velocity of the elevator u = -10 m/s

final velocity of the elevator v = 0 m/s

time taken to change velocity t = 3.0 s

Solution

a) Apparent weight before the braking

When the elevator is moving with a constant velocity, the only acceleration acts on Zach is the acceleration due to gravity

$W = mg\\\\W = 80 \times 9.8 \\\\W = 784 N$

b) Apparent weight during the braking

When the elevator is breaking, its velocity changes

So its acceleration

$a = \frac{\Delta v}{\Delta t} \\\\a = \frac{0-(-10)}{3} \\\\a = 3.33 m/s^2$

The positive sign indicates that the acceleration is acting upward

For upward acceleration, the apparent weight

$R = m(g+a)\\\\R = 80 ( 9.8 + 3.33)\\\\R = 1050.4 N$

You might be interested in

Most automobiles have a coolant reservoir to catch radiator fluid that may overflow when the engine is hot. A radiator is made o

Colt1911 [192]

Answer:

There is a loss of fluid in the container of 0.475L

Explanation:

To solve the problem it is necessary to take into account the concepts related to the change of voumen in a substance depending on the temperature.

The formula that describes this thermal expansion process is given by:

$\Delta V = \beta V_0 \Delta T$

Where,

$\Delta V =$ Change in volume

$V_0 =$ Initial Volume

$\Delta T =$ Change in temperature

$\beta =$ coefficient of volume expansion (Coefficient of copper and of the liquid for this case)

There are two types of materials in the container, liquid and copper, so we have to change the amount of Total Volume that would be subject to,

$\Delta V_T = \Delta V_l - \Delta V_c$

Where,

$\Delta V_l$ = Change in the volume of liquid

$\Delta V_c$ = Change in the volume of copper

Then replacing with the previous equation we have:

$\Delta V = \beta_l V_0 \Delta T- \beta_c V_0 \Delta T$

$\Delta V = (\beta_l-\beta_c)V_0\Delta T$

Our values are given as,

Thermal expansion coefficient for copper and the liquid to 20°C is

$\beta_c = 51*10^{-6}/\°C$

$\beta_l = 400*10^{-6}/\°C$

$V_0 = 16L$

$\Delta T = (95\°C-10\°C)$

Replacing we have that,

$\Delta V = (\beta_l-\beta_c)V_0\Delta T$

$\Delta V = (400*10^{-6}/\°C-51*10^{-6}/\°C)(16L)(95\°C-10\°C)$

$\Delta V = 0.475L$

Therefore there is a loss of fluid in the container of 0.475L

6 0

4 years ago

Which optical device can focus light to a point through reflection?

frosja888 [35]

Answer:

Explanation:

did the quiz

7 0

2 years ago

Whats A Controlled Experiment? Whats A Controlled Experiment? Like what the definition is please!

frozen [14]

A controlled experiment is when scientests go throw thests to make an experiment

3 0

3 years ago

For the following elementary reaction 2br• -> br2-. The rate of consumption of the reaction and the rate of formation of prod

Scorpion4ik [409]

Answer: $-\frac{1}{2}\times \frac{d[Br^.]}{dt}=+\frac{d[Br_2]}{dt}$

Explanation:

Rate of a reaction is defined as the rate of change of concentration per unit time.

Thus for reaction:

$2Br^.\rightarrow Br_2$

The rate in terms of reactants is given as negative as the concentration of reactants is decreasing with time whereas the rate in terms of products is given as positive as the concentration of products is increasing with time.

$Rate=-\frac{d[Br^.]}{2dt}$

or $Rate=+\frac{d[Br_2]}{dt}$

Thus $-\frac{d[Br^.]}{2dt}=+\frac{d[Br_2]}{dt}$

4 0

3 years ago

which of the following describes water changing from liqyid to solid, please give me a proof for this question please i really n

Fittoniya [83]

The answers A, this is because Ice is originally water and when water goes below it's freezing point it turns into ice

4 0

3 years ago

Read 2 more answers