Roots show ____. geotropism because they grow toward gravitational pull. 1.) positive 2.) neutral 3.) negative 3.)

In research in cardiology and exercise physiology, it is often important to know the mass of blood pumped by a person's heart in

frez [133]

Answer:

0.05081 kg

Explanation:

$m_1$ = Mass of blood

$v_1$ = 0.435 m/s

$m_2$ = Mass of subject and pallet = 54 kg

$v_2$ = Velocity of subject and pallet = $\dfrac{Distance}{Time}=\dfrac{6.55\times 10^{-5}}{0.16}=0.000409375\ m/s$

In this system the linear momentum is conserved so,

$m_1v_1=m_2v_2\\\Rightarrow m_1=\dfrac{m_2v_2}{v_1}\\\Rightarrow m_1=\dfrac{54\times 0.000409375}{0.435}\\\Rightarrow m_1=0.05081\ kg$

The mass of blood is 0.05081 kg

8 0

3 years ago

A soccer ball of mass 0.35 kg is rolling with velocity 0, 0, 1.8 m/s, when you kick it. Your kick delivers an impulse of magnitu

Mademuasel [1]

Answer:

position 9.58 m

Explanation:

In impulse exercises and amount of movement, we always assume that the contact time is small,

I = Δp

With this expression we can calculate the final speed

I = m Vf - m Vo

Vf = (I + mVo) / m

Vf = (1.8 + 0.35 1.8) /0.35

Vf = 6.94 m / s

To calculate the acceleration of the ball we use Newton's second law, after finishing the impulse

∑ F = m a

fr = m a

a = fr / m

a = -0.26 / 0.35

a = -0.74 m/s²

A negative sign indicates that this acceleration is slowing the ball

Now we have speed and time acceleration, so we can use the kinematic equations to find the position at 1.5 s

X = Vo t + ½ to t²

In this case Vo is the speed with which the ball comes out after the impulse 6.94

X = 6.94 1.5 + ½ (-0.74) 1.522

X = 9.58 m

7 0

3 years ago

A projectile is launched straight up from a height of 960 feet with an initial velocity of 64 ft/sec. Its height at time t is h(

Natasha2012 [34]

Answer:

a) $t=2s$

b) $h_{max}=1024ft$

c) $v_{y}=-256ft/s$

Explanation:

From the exercise we know the initial velocity of the projectile and its initial height

$v_{y}=64ft/s\\h_{o}=960ft\\g=-32ft/s^2$

To find what time does it take to reach maximum height we need to find how high will it go

b) We can calculate its initial height using the following formula

Knowing that its velocity is zero at its maximum height

$v_{y}^{2}=v_{o}^{2}+2g(y-y_{o})$

$0=(64ft/s)^2-2(32ft/s^2)(y-960ft)$

$y=\frac{-(64ft/s)^2-2(32ft/s^2)(960ft)}{-2(32ft/s^2)}=1024ft$

So, the projectile goes 1024 ft high

a) From the equation of height we calculate how long does it take to reach maximum point

$h=-16t^2+64t+960$

$1024=-16t^2+64t+960$

$0=-16t^2+64t-64$

Solving the quadratic equation

$t=\frac{-b±\sqrt{b^{2}-4ac}}{2a}$

$a=-16\\b=64\\c=-64$

$t=2s$

So, the projectile reach maximum point at t=2s

c) We can calculate the final velocity by using the following formula:

$v_{y}^{2}=v_{o}^{2}+2g(y-y_{o})$

$v_{y}=±\sqrt{(64ft/s)^{2}-2(32ft/s^2)(-960ft)}=±256ft/s$

Since the projectile is going down the velocity at the instant it reaches the ground is:

$v=-256ft/s$

5 0

3 years ago

What type of contraction requires the greatest amount of tension?

mars1129 [50]

Answer:

Isotonic eccentric

Explanation:

First of all, it should be noted that the term contraction has the meaning of joining or shortening. In the field of bodybuilding and workouts with loads, we can define muscle contraction as what happens whenever muscle fibers generate a tension in themselves.

This tension situation occurs in several situations, including when the muscle is shortened, elongated, moving, maintaining the same length or static.

There are different types of muscle contraction, among them we can highlight isotonic contraction, which is divided in turn into concentric and eccentric, isometric, auxotonic and isokinetic contraction.

Isotonic contraction is the most common type of contraction that occurs in most sports or physical activities that we perform in our day to day. Normally the muscular tensions that we exert are usually accompanied by a shortening and lengthening of the muscle fibers of a muscle. In turn, the isotonic contraction is divided into two, concentric and eccentric.

Concentric concentration: is that which happens when a muscle makes a tension capable of overcoming a resistance, producing a shortening and subsequent mobilization of a part of the body overcoming said resistance. For example, when we take a spoon and take it to our mouths to eat, a concentric shortening occurs. Putting examples in the gym on the bench press the movement of raising the bar, is equivalent to the concentric phase.

Eccentric concentration: we can say that it is one in which, given a resistance, we exert a greater tension with the muscle, so that said muscle is lengthened. In the case of the bench press, the eccentric phase is when we lower the bar to the chest.

8 0

3 years ago

A car starts from rest and accelerates along a straight line path in one minute it finally attains a velocity of 40 meters/secon

strojnjashka [21]

|Average acceleration| = (change in speed) / (time for the change)

Change in speed = (speed at the end) minus (speed at the beginning)

= (40 m/s) - ( 0 )

= 40 m/s .

|Average acceleration| = (40 m/s) / (60 sec) = 2/3 m/s² .

6 0

3 years ago