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aleksklad [387]
3 years ago
8

Erica (38 kgkg ) and Danny (46 kgkg ) are bouncing on a trampoline. Just as Erica reaches the high point of her bounce, Danny is

moving upward past her at 4.9 m/sm/s . At that instant he grabs hold of her.
Physics
1 answer:
salantis [7]3 years ago
6 0

Answer:

The speed with which just after he grabs her is 2.68 m/s.

Explanation:

Given that,

Mass of Erica, m = 38 m/s

Mass of Danny, m' = 46 kg

Erica reaches the high point of her bounce, Danny is moving upward past her at 4.9 m/s. At this moment, the initial speed of Erica will be 0. The momentum will remain conserved. Using the conservation of linear momentum as :

mu+m'u'=(m+m')V\\\\0+46\times 4.9=(38+46)V\\\\V=\dfrac{225.4}{84}\\\\V=2.68\ m/s

So, the speed with which just after he grabs her is 2.68 m/s. Hence, this is the required solution.

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Electromagnetic waves can transfer energy without a(n) _____________ (medium/electric field).
KATRIN_1 [288]
Medium.
Medium is matter, and electromagnetic waves do not need matter to travel. Just like the sun, its plasma light travels across space to reach us.
7 0
3 years ago
A bug is 12 cm from the center of a turntable that is rotating with a frequency of 45 rev/min . What minimum coefficient frictio
Agata [3.3K]

Answer:

The minimum coefficient of friction is 0.27.

Explanation:

To solve this problem, start with identifying the forces at play here. First, the bug staying on the rotating turntable will be subject to the centripetal force constantly acting toward the center of the turntable (in absence of which the bug would leave the turntable in a straight line). Second, there is the force of friction due to which the bug can stick to the table. The friction force acts as an intermediary to enable the centripetal acceleration to happen.

Centripetal force is written as

F_c = m\frac{v^2}{r}

with v the linear velocity and r the radius of the turntable. We are not given v, but we can write it as

v = r\omega

with ω denoting the angular velocity, which we are given. With that, the above becomes:

F_c = m\frac{v^2}{r}=m\omega^2 r

Now, the friction force must be at least as much (in magnitude) as Fc. The coefficient (static) of friction μ must be large enough. How large?

F_r=\mu mg \geq m\omega^2 r = F_c\implies\\\mu \geq \frac{\omega^2 r}{g}

Let's plug in the numbers. The angular velocity should be in radians per second. We are given rev/min, which can be easily transformed by a factor 2pi/60:

\frac{1 rev}{1 min}\cdot\frac{\frac{2\pi rad}{rev}}{\frac{60s}{1 min}}=\frac{2\pi}{60}\frac{rad}{s}

and so 45 rev/min = 4.71 rad/s.

\mu \geq \frac{\omega^2 r}{g}=\frac{4.71^2\frac{1}{s^2}\cdot 0.12m}{9.8\frac{m}{s^2}}=0.27

A static coefficient of friction of at least be 0.27 must be present for the bug to continue enjoying the ride on the turntable.



3 0
3 years ago
A strip of copper 190 µm thick and 4.20 mm wide is placed in a uniform magnetic field of magnitude B = 0.78 T, that is perpendic
Veronika [31]

Answer:

V = 9.682 × 10^(-6) V

Explanation:

Given data

thick = 190 µm

wide = 4.20 mm

magnitude B = 0.78 T

current  i = 32 A

to find out

Calculate V

solution

we know v formula that is

V = magnitude× current / (no of charge carriers ×thickness × e

here we know that number of charge carriers/unit volume for copper = 8.47 x 10^28 electrons/m³

so put all value we get

V = magnitude× current / (no of charge carriers ×thickness × e

V = 0.78 × 32 / (8.47 x 10^28  × 190 × 1.602 x 10^(-19)

V = 9.682 × 10^(-6) V

3 0
3 years ago
Improving your cardiovascular endurance, such as aerobic activity, can get your heart pumping, make you sweaty, and quicken your
Thepotemich [5.8K]

Answer:

The correct answer is - oxygen.

Explanation:

Cardiovascular endurance is the ability to do physical activity or exercise without affecting or being tired for a longer time period. Aerobic exercise or activity can help to increase cardiovascular endurance.

Improving the cardiovascular system helps in delivering oxygen as per the demands with the help of the heart that pumps the oxygen-rich blood to different organs of an individual and lungs by inhaling enough oxygen.

5 0
3 years ago
A rocket is launched from the launch pad at a speed of 700 km/hr.
Juliette [100K]

Answer:

Explanation:

Vm = Δs/Δt

700km/h = Δs/1.5h

700 = Δs/1.5

\frac{700}{1} = \frac{S}{1.5}

S = 700 x 1.5

S = 1050 Km

*(S = Δs)

Answer: The rocket will have traveled 1050 Km

Hope this help ☺

5 0
3 years ago
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