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3 years ago

What’s contact force ?

Physics

2 answers:

kodGreya [7K]3 years ago

5 0

Explanation:

Contact force is any force that requires contact. An object that exerts a force on another object by touching it is exerting a contact force. Examples of contact force are friction and normal force.

Examples of a non-contact force are gravity and magnetism.

natima [27]3 years ago

4 0

Any force that requires contact force

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A diver jumps off a cliff 50m high and needs to clear the rock that extend outward 5.0m from the base of the cliff. The diver ju

igor_vitrenko [27]

Answer:

He should run at least at 1.5 m/s

The diver will enter the water at an angle of 87° below the horizontal.

Explanation:

Hi there!

The position and velocity of the diver are given by the following vectors:

r = (x0 + v0x · t, y0 + v0y · t + 1/2 · g · t²)

v = (v0x, v0y + g · t)

Where:

r = position vector at time t

x0 = initial horizontal position

v0x = initial horizontal velocity

t = time

y0 = initial vertical position

v0y = initial vertical velocity

g = acceleration due to gravity (-9.8 m/s² considering the upward direction as positive)

v = velocity vector at time t

Please, see the attached figure for a description of the problem. Notice that the origin of the frame of reference is located at the jumping point so that x0 and y0 = 0.

We know that, to clear the rocks, the position vector r final (see figure) should be:

r final = ( > 5.0 m, -50 m)

So let´s find first at which time the y-component of the vector r final is - 50 m:

y = y0 + v0y · t + 1/2 · g · t²

-50 m = 2.1 m/s · t - 1/2 · 9.8 m/s² · t²

0 = -4.9 m/s² · t² + 2.1 m/s · t + 50 m

Solving the quadratic equation

t = 3.4 s

Now, we can calculate the initial horizontal velocity using the equation of the x-component of the position vector knowing that at t =3.4 the horizontal component should be greater than 5.0 m:

x = x0 + v0x · t (x0 = 0)

5.0 m < v0x · 3.4 s

v0x > 5.0 m / 3.4 s

v0x > 1.5 m/s

The initial horizontal velocity should be greater than 1.5 m/s

To find the angle at which the diver enters the water, we have to find the magnitude of the final velocity (vector vf in the figure). We already know the magnitude of the x-component of the vector vf, since the horizontal velocity is constant. So:

vfx > 1.5 m/s

Now, let´s calculate vfy:

vfy = v0y + g · t

vfy = 2.1 m/s - 9.8 m/s² · 3.4 s

vfy = -31 m/s

Let´s calculate the minimum magnitude that the final velocity will have if the diver safely clears the rocks. Let´s consider the smallest value allowed for vfx: 1.5 m/s. Then:

$|v| = \sqrt{(1.5 m/s)^{2} + (31m/s)^{2}} = 31 m/s$

Then the final velocity of the diver will be greater or equal than 31 m/s.

To find the angle, we have to use trigonometry. Notice in the figure that the vectors vf, vfx and vy form a right triangle in which vf is the hypotenuse, vfx is the adjacent side and vfy is the opposite side to the angle. Then:

cos θ = adjacent / hypotenuse = vfx / vf = 1.5 m/s / 31 m/s

θ = 87°

The diver will enter the water at an angle of 87° below the horizontal.

8 0

3 years ago

What is an unbalanced force

Butoxors [25]

There's no such thing as "an unbalanced force".

If all of the forces acting on an object all add up to zero, then we say that
the group of forces is balanced. When that happens, the group of forces
has the same effect on the object as if there were no forces on it at all.

An example:
Two people with exactly equal strength are having a tug-of-war. They pull
with equal force in opposite directions. Each person is sweating and straining,
grunting and groaning, and exerting tremendous force. But their forces add up
to zero, and the rope goes nowhere. The group of forces on the rope is balanced.

On the other hand, if one of the offensive linemen is pulling on one end of
the rope, and one of the cheerleaders is pulling on the other end, then their
forces don't add up to zero, because even though they're opposite, they're
not equal. The group of forces is unbalanced, and the rope moves.

A group of forces is either balanced or unbalanced. A single force isn't.

7 0

3 years ago

Starting from the front door of your ranch house, you walk 50.0 m due east to your windmill, and then you turn around and slowly

Hunter-Best [27]

Answer:

Average velocity

$v=\frac{d}{t}\\ v=\frac{10m}{70s}\\v=.1428 \frac{m}{s}$

Average speed,

$S=\frac{D}{t}\\ S=\frac{90}{70}\\ S=1.29\frac{m}{s}$

Explanation:

(a)Average velocity

We have to find the average velocity. We know that velocity is defined as the rate of change of displacement with respect to time.

To find the average velocity we have to find the total displacement.

since displacement along east direction is 50m

and displacement along west=40m

so total displacement,

$d=50m-40m\\d=10m$

total time,

$t=28 s+42 s\\t=70 s$

therefore, average velocity

$v=\frac{d}{t}\\ v=\frac{10m}{70s}\\v=.1428 \frac{m}{s}$

(b)Average Speed:

Average speed is defined as the ratio of total distance to the total time

it means

Average speed= total distance/total time

here total distance,

$D= 50m+40m\\D=90m$

and total time,

$t= 28s+40s\\t=70s$

therefore,

Average speed,

$S=\frac{D}{t}\\ S=\frac{90}{70}\\ S=1.29\frac{m}{s}$

8 0

3 years ago

. A bead of mass m under the influence of gravity slides along a frictionless and massless wire whose height is given by a funct

eduard

Answer:

y = constant

Explanation:

Bodies moving on the surface of Earth are subject to gravity, and they have a potential and kinetic energy. If there is no friction, the sum of the kinetic and potential energy remains constant.

Since potential energy depends on height, changes in altitude affect potential energy. Going higher increases this energy, this is accompanied by a reduction of kinetic energy and speed (since kinetic energy is related to speed). If the body goes down potential energy is reduced, but kinetic energy and speed increase.

For speed to remain constant the kinetic energy must remain constant. For the kinetic energy to remanin constant, the potential energy must remain constant, and for the potential energy to remain constant the height must remain constant.

7 0

3 years ago

When an electric current is passed through water during the process of electrolysis two gases are formed one gas has a boiling p

vagabundo [1.1K]

There is a chemical change because the liquid water, after passing an electric current, produces hydrogen and oxygen gases. This is a reaction. The molecular component of eater has been broken down into two. These two gases have different structures compared to water.

3 0

3 years ago

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