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Ann [662]
3 years ago
13

A sled slides down a hill, reaches the level surface, and eventually comes to a stop. Which fact ultimately explains why the sle

d stops?
A. The presence of an unbalanced force causes an object to move forward at constant velocity
B. The presence of an unbalanced force (e.g. friction) causes a moving object to stop
C. The presence of inertia causes a moving object to stop
D. The natural tendency of any object is to ultimately stop
Physics
1 answer:
Kitty [74]3 years ago
7 0

Answer:

B. The presence of an unbalanced force(e.g friction) causes a moving object to stop.

Explanation:

As the friction is that force that can stop the sled upon reaching the levelled surface so the option b is correct.

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One end of a thin rod is attached to a pivot, about which it can rotate without friction. Air resistance is absent. The rod has
Scrat [10]

Answer:

5.24 m/s

Explanation:

So for the rod to be able to rise upward to the straight up position, the kinetic energy caused by linear speed v0 must be just enough to convert into the potential energy.

Since the rod is uniform in mass, we can treat the body as 1 point, at its center of mass, or geometric center, aka 0.35 / 2 = 0.175 m from the pivot.

For the rod to swing from bottom to top, the center must have moved a distance of h = 0.175 * 2 = 0.35 m, vertically speaking.

Since we neglect friction and air resistance, according to the law of energy conservation then:

E_k = E_p

mv^2/2 = mgh

Where v is the speed at the center of mass, g = 9.81 m/s2 is the gravitational acceleration, and m is the mass. We can divide both sides by m

v^2 = 2gh = 2*9.81*0.35 = 6.867

v = \sqrt{6.867} = 2.62 m/s

As this is only the speed at the center of mass, the speed at the bottom end would be different, to calculate this, we need to find the common angular speed:

\omega = v / r = 2.62 / 0.175 = 14.97 rad/s

Where r is the rotation radius, or the distance from pivot point to the center of mass

v_0 = \omega R = 14.97*0.35 = 5.24 m/s

Where R is the distance from the pivot to the bottom end of the rod

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How does earth's magnetic field behave through long periods of geologic time?
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Yanka [14]

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A 0.0780 kg lemming runs off a
kotegsom [21]

Answer:

5.01 J

Explanation:

Info given:

mass (m) = 0.0780kg

height (h) = 5.36m

velocity (v) = 4.84 m/s

gravity (g) = 9.81m/s^2

1. First, solve for Kinetic energy (KE)

KE = 1/2mv^2

1/2(0.0780kg)(4.84m/s)^2 = 0.91 J

so KE = 0.91 J

2. Next, solve for Potential energy (PE)

PE = mgh

(0.0780kg)(9.81m/s^2)(5.36m) = 4.10 J

so PE = 4.10 J

3. Mechanical Energy , E = KE + PE

Plug in values for KE and PE

KE + PE = 0.91J + 4.10 J = 5.01 J

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Write a note on unity of ant​
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Explanation: search for it.

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