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11111nata11111 [884]

3 years ago

15

"A boat that can travel at 4.0 km/h in still water crosses a river with a current of 2.0 km/h. At what angle must the boat be po

inted upstream (that is, relative to its actual path) to go straight across the river?

1 answer:

IRISSAK [1]3 years ago

8 0

Answer:

30 degrees

Explanation:

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1 A thing ring has a mass of 6kg and a radius of 20cm. calculate the rotational inertia.

marissa [1.9K]

Answer:

2400kgm²

Explanation:

Rotational inertia=mass x radius²

7 0

3 years ago

5.An ice skater pushes against a wall with a force of 59 N. Ignoring friction, if the ice skater has

natali 33 [55]

Answer:

<em>Answer: (A) 0.75 m/s^2</em>

Explanation:

The Second Newton's law states that an object acquires acceleration when an external unbalanced net force is applied to it.

That acceleration is proportional to the net force and inversely proportional to the mass of the object.

It can be expressed with the formula:

$\displaystyle a=\frac{F_n}{m}$

Where

Fn = Net force

m = mass

The ice skater pushes against a wall with a force of 59 N. The wall returns the force and the skater now has a net force of Fn=59 N that makes him accelerate. Being m=79 kg the mass of the skater, the acceleration is:

$\displaystyle a=\frac{59}{79}$

$a = 0.75\ m/s^2$

Answer: (A) 0.75 m/s^2

5 0

3 years ago

In a uniform circular motion map, what is always true? Check all that apply.

grandymaker [24]

Answer:

Velocity vectors are always perpendicular to the circle.

Acceleration vectors point toward the center of the circle.

Velocity vectors are the same length.

Explanation:

(THESE ARE NOT MY WORDS BTW)

1) Acceleration and velocity are vectorial quantities, which means they have magnitude and direction.

2) In a circular motion velocity direction changes all the time, which means that it is accelerated.

3) In a uniform circular motiion, the velocity changes in a constant value. This is the rate of change of velocity, which is the magnitude of the acceleration, is constant (uniform).

4) The velocity is perpendicular to the path, i.e. the circle. You can see it if you think that if the object stopped changing the direction, then the object would follow a straight path (as per inertia principle). That is why this velocity is called tangential velocity (to differentiate it of the angular velocity).

This is what the option C says "Velocity vectors are always perpendicular to the circle". Then this is true.

5) The constant change of direction in a circular path, means that the object is been pushed, accelerated, toward the center of a circle. This is, all the time the object in motion tries to follow the perpendicular path but a push (a force) directed to the center of the circle changes its direction. Such force accelerates the object toward the center of the circle. So, the acceleration vectors point toward the center of the circle, which is what the option D says. So, this is also true.

6) Since the motion is uniform, the magnitude or length of the velocity vectors are always the same, are constant. So, the option E. is also true.

6 0

3 years ago

Read 2 more answers

In a fast-pitch softball game the pitcher is impressive to watch, as she delivers a pitch by rapidly whirling her arm around so

Pepsi [2]

Answer:

(a) 181.05 m/s²

(b) 13.2°

Explanation:

Given:

Radius of the circle (R) = 0.610 m

Angular acceleration (α) = 67.6 rad/s²

Angular speed (ω) = 17.0 rad/s

(a)

Radial acceleration of the ball is given as:

$a_r=\omega^2R$

Plug in the given values and solve for $a_r$ . This gives,

$a_r=(17.0\ rad/s)^2\times (0.610\ m)\\\\a_r=289\times 0.610\ m/s^2\\\\a_r=176.29\ m/s^2$

Now, tangential acceleration is given by the formula:

$a_t=R\alpha$

Plug in the given values and solve for $a_t$ . This gives,

$a_t=(0.610\ m)(67.6\ rad/s^2)\\\\a_t=41.236\ m/s^2$

Now, the magnitude of total acceleration is given as the square root of the sum of the squares of tangential and centripetal accelerations. Therefore,

$a_{Total}=\sqrt{(a_r)^2+(a_t)^2}$

Plug in the given values and solve for total acceleration, $a_{Total}$ . This gives,

$a_{Total}=\sqrt{(176.29)^2+(41.236)^2}\\\\a_{Total}=181.05\ m/s^2$

Therefore, the magnitude of total acceleration is 181.05 m/s².

(b)

Angle of total acceleration relative to radial direction is given by the formula:

$\theta=\tan^{-1}(\frac{a_t}{a_r})\\\\\theta=\tan^{-1}(\frac{41.236}{176.29})\\\\\theta=13.2\°$

Therefore, the total acceleration makes an angle of 13.2° relative to radial direction.

4 0

3 years ago

As a truck rounds a curve, a box in the bed of the truck slides to the side farthest from the center of the curve. This movement

Bumek [7]

Because I don’t have choices I’m not sure what to chose from or what the subject is about but I can tell you that the box moves from the result of Inertia, and is kenetic energy

3 0

2 years ago