The center of ?

Cohort studies allow the investigator to examine multiple outcomes and multiple exposures. Consider the following three exposure

mojhsa [17]

Answer:

See the explanation for the answer.

Explanation:

Cohort study for smoking

Outcomes that were examined

1. People at risk of lung cancer due to smoking

2. Influence of outdoor air pollution in lung cancer

3. Variation in tobacco smoking and heavy tobacco smoking was observed.

4. Occupational factors and housing factor were observed.

Cohort study for low vitamin D

Outcomes that were examined

1. People at risk of vitamin D deficiency.

2. Observing value in summer.

3. Correlating vitamin D value with weather and age

4. 25-hydroxy vitamin D was observed.

Cohort study for cold weather

Outcomes that were examined

1. Allergic and asthma risked people were observed.

2. effect on the people when temperature goes up.

3. Observation on the most harsh weather day.

4. Correlating it with age and analysis.

3 0

3 years ago

Which would exert the most gravity on a spacecraft that is passing close to Jupiter?

klio [65]

D. Jupiter has the highest amount of gravity in our solar system

7 0

2 years ago

Which two formulas are used to calculate potential and kinetic energy

goblinko [34]

Answer:

gravitational potential energy:

GPE = m g h

kinetic energy:

KE = 1/2 m v^2

6 0

2 years ago

Read 2 more answers

For a freely falling object weighing 3 kg : A. what is the object's velocity 2 s after it's release. B. What is the kinetic ener

Fed [463]

A) 19.6 m/s (downward)

B) 576 J

C) 19.6 m

D) Velocity: not affected, kinetic energy: doubles, distance: not affected

Explanation:

A)

An object in free fall is acted upon one force only, which is the force of gravity.

Therefore, the motion of an object in free fall is a uniformly accelerated motion (constant acceleration). Therefore, we can find its velocity by applying the following suvat equation:

$v=u+at$

where:

v is the velocity at time t

u is the initial velocity

$a=g=9.8 m/s^2$ is the acceleration due to gravity

For the object in this problem, taking downward as positive direction, we have:

$u=0$ (the object starts from rest)

$a=9.8 m/s^2$

Therefore, the velocity after

t = 2 s

is:

$v=0+(9.8)(2)=19.6 m/s$ (downward)

B)

The kinetic energy of an object is the energy possessed by the object due to its motion.

It can be calculated using the equation:

$KE=\frac{1}{2}mv^2$

where

m is the mass of the object

v is the speed of the object

For the object in the problem, at t = 2 s, we have:

m = 3 kg (mass of the object)

v = 19.6 m/s (speed of the object)

Therefore, its kinetic energy is:

$KE=\frac{1}{2}(3)(19.6)^2=576 J$

C)

In order to find how far the object has fallen, we can use another suvat equation for uniformly accelerated motion:

$s=ut+\frac{1}{2}at^2$

where

s is the distance covered

u is the initial velocity

t is the time

a is the acceleration

For the object in free fall in this problem, we have:

u = 0 (it starts from rest)

$a=g=9.8 m/s^2$ (acceleration of gravity)

t = 2 s (time)

Therefore, the distance covered is

$s=0+\frac{1}{2}(9.8)(2)^2=19.6 m$

D)

Here the mass of the object has been doubled, so now it is

M = 6 kg

For part A) (final velocity of the object), we notice that the equation that we use to find the velocity does not depend at all on the mass of the object. This means that the value of the final velocity is not affected.

For part B) (kinetic energy), we notice that the kinetic energy depends on the mass, so in this case this value has changed.

The new kinetic energy is

$KE'=\frac{1}{2}Mv^2$

where

M = 6 kg is the new mass

v = 19.6 m/s is the speed

Substituting,

$KE'=\frac{1}{2}(6)(19.6)^2=1152 J$

And we see that this value is twice the value calculated in part A: so, the kinetic energy has doubled.

Finally, for part c) (distance covered), we see that its equation does not depend on the mass, therefore this value is not affected.

5 0

2 years ago

A wave has a frequency of 6 Hz and a speed of 30 m/s. What is the wavelength of the wave?

Helen [10]

Answer:

D. 5m

Explanation:

fλ = c, where f is frequency, λ is wavelength and c is speed.

6λ=30

λ=30/6=5

5 0

2 years ago