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vova2212 [387]
3 years ago
8

A cat dozes on a stationary merry-go-round, at a radius of 5.5 m from the center of the ride. Then the operator turns on the rid

e and brings it up to its proper turning rate of one complete rotation every 6.3 s. What is the least coefficient of static friction between the cat and the merry-go-round that will allow the cat to stay in place, without sliding
Physics
1 answer:
bixtya [17]3 years ago
6 0

Answer:

u_{s}=0.56

Explanation:

For the cat to stay in place on the merry go round without sliding the magnitude of maximum static friction must be equal to magnitude of centripetal force

F_{s.max}=\frac{mv^2}{r} \\

Where the r is the radius of merry-go-round and v is the tangential speed

but

F_{s.max}=u_{s}F_{N}=u_{s}mg

So we have

u_{s}mg=\frac{mv^2}{r}\\ u_{s}=\frac{v^2}{gr}\\ Where\\v=\frac{2\pi R}{T} \\So\\u_{s}=\frac{(\frac{2\pi R}{T} )^2}{gr} \\u_{s}=\frac{4\pi^2 r}{gT^2}

Substitute the given values

So

u_{s}=\frac{4\pi^2 5.5m}{(9.8m/s^2)(6.3s)^2} \\u_{s}=0.56

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Sarah, who has a mass of 55 kg, is riding in a car at 20 m/s. She sees a cat crossing the street and slams on the brakes! Her se
avanturin [10]

Answer:

-2200 N

Explanation:

The change in momentum of Sarah is equal to the impulse, which is the product between the force exerted by the seatbelt on Sarah and the time during which the force is applied:

\Delta p=I\\m \Delta v = F \Delta t

where

m is the mass

\Delta v is the change in velocity

F is the average force

\Delta t is the duration of the collision

In this problem:, we have:

m = 55 kg is Sarah's mass

\Delta v = 0-20 = -20 m/s  is the change in velocity

\Delta t = 0.5 s  is the duration of the collision

Solving for F, we find the force exerted by the seatbelt on Sarah:

F=\frac{m\Delta v}{\Delta t}=\frac{(55)(-20)}{0.5}=-2200 N

Where the negative sign indicates that the direction of the force is opposite to that of Sarah's initial velocity.

5 0
3 years ago
This is a machine that converts electrical energy into mechanical energy.
Yuri [45]
<h2>Answer:</h2>

Motor

<h2>Explanation:</h2>

A motor is a machine that converts electrical energy into mechanical energy. In motors, electric energy is converted into mechanic energy when a magnetic torque acts on a conductor that carries a current. There are different types of motors like DC and AC motors. The moving part of a motor is called the rotor while the stationary part is called stator

8 0
3 years ago
You can use _______________ to change a liquid into a gas.
Nitella [24]

Answer:

below

Explanation: When a liquid changes into a gas vaporization has occurred. The process can either occur due to boiling or evaporation. Boiling occurs when the vapor pressure of the liquid is raised (by heating) to the point where it is equal to the atmospheric pressure.

7 0
3 years ago
A gang of robbers is escaping across city roofs at night. They come to the edge of one building and need to drop down to their g
REY [17]

Answer:

a) They will hit the ground with a speed of 19.6 m/s.

b) They are at a height of 20 m.

c) It is not a safe jump.

Explanation:

Hi there!

a) The equations of height and velocity in function of time of a free falling body are the following:

h = h0 + v0 · t + 1/2 · g · t²

v = v0 + g · t

Where:

h = height of the object at time t.

h0 = initial height.

v0 = initial velocity.

t = time.

g = acceleration due to gravity (-9.8 m/s² considering downward as negative direction).

v = velocity of the object at time t.

Using the equation of velocity, let's find the velocity at which they will hit the ground. The pebble is dropped (initial velocity = 0) and it takes 2 s to reach the ground:

v = v0 + g · t     (v0 = 0)

v = g · t

v = -9.8 m/s² · 2.0 s

v = -19.6 m/s

They will hit the ground with a speed of 19.6 m/s.

b)Now, we have to use the equation of height:

h = h0 + v0 · t + 1/2 · g · t²

If we place the origin of the frame of reference on the ground, we have to find the initial height (h0) knowing that at t = 2.0 s, h = 0 m

0 m = h0 - 1/2 · 9.8 m/s² · (2.0 s)²

h0 = 1/2 · 9.8 m/s² · (2.0 s)²

h0 = 20 m

They are at a height of 20 m.

c)According to a NASA paper (Issues on Human Acceleration Tolerance After Long-Duration Space Flights, figure 10), if you fall with a vertical velocity greater than 17 m/s it is unlikely that you will survive. So, it is not a safe jump.  

3 0
3 years ago
Three identical resistors are connected in parallel to a battery. If the current of 12. A flows from the battery, how much curre
Doss [256]

Answer:

4 A

Explanation:

We are given that

R_1=R_2=R_3=4\Omega

I=12 A

We have to find the current flowing through each resistor.

We know that in parallel combination current flowing through different resistors are different and potential difference across each resistor is same.

Formula :

\frac{1}{R}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}

Using the formula

\frac{1}{R}=\frac{1}{4}+\frac{1}{4}+\frac{1}{4}=\frac{3}{4}

R=\frac{4}{3}\Omega

V=IR

Substitute the values

V=12\times \frac{4}{3}=16 V

I_1=\frac{V}{R_1}=\frac{16}{4}=4 A

I_1=I_2=I_3=4 A

Hence, current flows through any one of the resistors is 4 A.

7 0
3 years ago
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