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3 years ago

Describe what happens when you jump from a small boat onto a dock from the perspective of the 3rd Law.

1 answer:

5 0

according to newton's third law, every action has equal and opposite reaction. in this scenario of making a jump from the boat onto a dock, as i jump my feet in contact with the boat push the boat in backward direction. hence the action force is the push by my feet on the boat. the boat reacts by applying a reaction force on my feet pushing the feet in forward direction. hence reaction force here is the force by the boat on the feet. due to the reaction force of the boat on feet, i am pushed in forward direction to reach the the dock.

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An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the ten

VikaD [51]

Answer:

C. The net work done by the two forces is zero joules.

Explanation:

Work (W) is defined as the product of force F) by the distance (d)the body travels due to this force.

W= F*d Formula ( 1)

The work is positive (W+) if the force has the same direction of movement of the object.

The work is negative (W-) if the force has the opposite direction of the movement of the object.

The component of the force that performs work must be parallel to the displacement.

Calculation of the forces

We apply Newton's second law:

∑F = m*a

∑F : algebraic sum of the forces in Newton (N)

m : mass in kilograms (kg)

a : acceleration in meters over second square (m/s²)

∑F = m*a

a = 0 because the elevator moves at constant speed.

∑F=0

T-W = 0

T = W

Calculation of work done by the forces

W₁ : work done by the gravity= (+ W*d ) J

W₂ : work done by the tension force=( -T*d) J

Net work done by the two forces(W₁-W₂):

W₁= W₂ .because T = W

W₁-W₂ =0

3 0

3 years ago

You are planning to make an open rectangular box from an 8-inch by 15-inch piece of cardboard by cutting congruent squares from

Phoenix [80]

Let us say that x is the cut that we will make on the sides to make a box, therefore the new dimensions are:

l = 15 – 2x

w = 8 – 2x

It is 2x since we cut on two sides.

We know that volume is:

V = l w x

V = (15 – 2x) (8 – 2x) x

V = 120x – 30x^2 – 16x^2 + 4x^3

V = 120x – 46x^2 + 4x^3

Taking the 1st derivative:

dV/dx = 120 – 92x + 12x^2

Set dV/dx = 0 to get maxima:

120 – 92x + 12x^2 = 0

Divide by 12:

x^2 – (92/12)x + 10 = 0

(x – (92/24))^2 = -10 + (92/24)^2

x - 92/24 = ±2.17

x = 1.66, 6

We cannot have x = 6 because that will make our w negative, so:

x = 1.66 inches

So the largest volume is:

V = 120x – 46x^2 + 4x^3

V = 120(1.66) – 46(1.66)^2 + 4(1.66)^3

V = 90.74 cubic inches

4 0

4 years ago

A rock is thrown downward from an unknown height above the ground with an initial speed of 6.1 m/s. It strikes the ground 1.7 s

insens350 [35]

Answer:

24.531 m

Explanation:

t = Time taken = 1.7 s

u = Initial velocity = 6.1 m/s

v = Final velocity

s = Displacement

g = Acceleration due to gravity = 9.81 m/s² = a

Equation of motion

$s=ut+\dfrac{1}{2}at^2\\\Rightarrow s=6.1\times 1.7+\dfrac{1}{2}\times 9.8\times 1.7^2\\\Rightarrow s=24.531\ m$

The initial height of the rock above the ground is 24.531 m

7 0

3 years ago

The angular speed of digital video discs (DVDs) varies with whether the inner or outer part of the disc is being read. (CDs func

Kitty [74]

Answer:

α = 0.0135 rad/s²

Explanation:

given,

t = 133 min = 133 x 60 = 7980 s

angular speed varies from 570 rpm to 1600 rpm

now,

570 rpm = $570 \times \dfrac{2\pi}{60}$

= 59.69 rad/s

1600 rpm = = $570 \times \dfrac{2\pi}{60}$

= 167.6 rad/s

using equation of rotational motion

ωf = ωi + αt

167.6 = 59.7 + α x 7980

α x 7980 = 107.9

α = 0.0135 rad/s²

8 0

3 years ago

A potential energy function is given by U(x)=(3.00J)x+(1.00J/m2)x3. What is the force function F(x) (in newtons) that is associa

Anit [1.1K]

Answer:

$F(x)=-3 N - (3N)x^2$

Explanation:

The force is defined as the negative of the derivative of the potential energy:

$F=-\frac{dU}{dx}$

If we use the potential energy function given in this problem:

$U(x)=3.00 x + 1.00 x^3$

and we calculate the force, we get:

$F(x)=-\frac{d}{dx}(3x+x^3)=-3-3x^2$

So, the force is

$F(x)=-3 N - (3N)x^2$

5 0

3 years ago

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