Pleaseeee help!!!! I will mark you as brainlinest for correct answer!!!!!!!

A 210-kg woorden raft floats on a lake. When a 75-kg man stands on the raft, it sinks 5.0 cm deeper into the water. When he step

GaryK [48]

Answer:

A: The frequency of the vibration is 1.3329 Hz

B: The total energy of the vibration is 18.39375 J

Explanation:

The force of the man his weight causes the raft to sink, and that causes the water to put a larger upward force on the raft. This extra force is a restoring force, because it is in the opposite direction of the force put on the raft by the man. Then when the man steps off, the restoring force pushes upward on the raft, and thus the raft – water system acts like a spring, with a spring constant found as follows:

k= F/x = ((75 kg) * (9.81 m/s²))/(5*10^-2 m) = 14715 N/m

The frequency of the vibration is determined by the spring constant (k) and the mass of the raft (210kg).

fn = 1/2π * √(k/m) = 1/2π * √(14715 / 210) = 1.3329 Hz

The frequency of the vibration is 1.3329 Hz

b)

Since the gravitational potential energy can be ignored, the total energy will be :

Etot = 1/2 k* A² = 1/2 * (14715 )*(0.05)² = 18.39375 J

The total energy of the vibration is 18.39375 J

7 0

3 years ago

Which of the following statements uses a connotative word to evoke the most negative feeling?

irga5000 [103]

I think it’ll be a or d

7 0

2 years ago

Read 2 more answers

The freezer compartment in a conventional refrigerator can be modeled as a rectangular cavity 0.3 m high and 0.25 m wide with a

Anon25 [30]

Answer:

Thickness of Styrofoam insulation is 0.02741 m.

Explanation:

Given that,

Height = 0.25 m

Depth = 0.5 m

Power = 400 W

Temperature = 33°C

We need to calculate the area of Styrofoam

Using formula of area

$A=2(lb+bh+hl)$

Put the value into the formula

$A=2(0.3\times0.5+0.25\times0.5+0.5\times0.3)$

$A=0.85\ m^2$

Inner surface temperature of freezer

$T_{i}=-10°C=263\ K$

Outer surface temperature of freezer

$T_{o}=33+273=306\ K$

We need to calculate the thickness of Styrofoam insulation

Using Fourier law,

$q=\dfrac{kA}{L}(T_{o}-T_{i})$

$L=\dfrac{kA}{q}(T_{o}-T_{i})$

Put the value into the formula

$L=\dfrac{0.30\times0.85}{400}(306-263)$

$L=0.02741\ m$

Hence, Thickness of Styrofoam insulation is 0.02741 m.

8 0

3 years ago

When a board with a box on it is slowly tilted to larger and larger angle, common experience shows that the box will at some poi

eimsori [14]

Answer: The force of kinetic friction is smaller than that of static friction, but F_g remains the same.

Explanation:

The situation is same as when a book is pushed with an increasing force on a table; When the force is low, book doesn't move, until that under a given force starts moving, and then it goes on movement even if the force decreases a bit.

The physical explanation for this, that friction force adopts any value needed to avoid to move the object, till a limit value is achieved, called static friction force, equal to the normal force times the static friction coefficient.

Once in movement, the kinetic friction coefficient replaces the static one , and in general is lower than the static one, so the force diminishes.

In the case of the box sliding down the board, the force that tries to move the object down the board, is the component of the weight parallel to the board, that can be showed that being equal to the weight times the sinus of the angle of the board with the horizontal, as follows:

F_g = m g sin θ

When θ increases, F_g does the same, so friction force always has the same magnitude than F_g (but opposite direction) so the box doesn't move, till that θ takes a value that produces a F_g equal to static friction force.

Beyond this limit angle, F_g (remaining the same for a given angle) is greater than the kinetic friction force, and the box slides.

In the limit, when θ=90º, sin θ =1⇒ F_g = mg, so the object is in free fall.

6 0

3 years ago

What is the gravitational force between Mars and the sun? 7.43 × 1030 N 1.79 × 1026 N 1.65 × 1021 N 3.76 × 1032 N

VMariaS [17]

The gravitational force between Mars and the Sun is $1.65\cdot 10^{21} N$