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2 years ago

5. The net external force on a rock of mass 4.2 kg is 8.0 N forward. Find the acceleration of the rock.

Physics

1 answer:

andreev551 [17]2 years ago

6 0

Answer:

1.904

Explanation:

F= ma

8 = 4.2 a

a = 8/4.2

a = 1.904

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A 0.2 kg hockey puck moving at 80 m/s is caught by a 40 kg goalie at rest. With what speed does the goalie slide on the slide?

Lady_Fox [76]

Answer:

V = 0.39 m/s

Explanation:

Given that,

Mass of hockey puck, m = 0.2 kg

Mass of goalie = 40 kg

Speed of hockey puck, v = 80 m/s

We need to find the speed with which the goalie slide on the slide. Let V be the speed. Using the conservation of momentum as follows :

$mv=(M+m)V\\\\V=\dfrac{mv}{M+m}\\\\V=\dfrac{0.2\times 80}{0.2+40}\\\\V=0.39\ m/s$

So, the required speed is 0.39 m/s.

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2 years ago

What is the acceleration of a 0.90g drop of blood in the fingertips at the bottom of the swing?

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The acceleration of a 0.90 g drop of blood in the fingertips at the bottom of the swing is the sum of the acceleration of the movement of the finger and the acceleration of gravity. In this case, this is different when the finger goes down, since the acceleration now becomes the difference between the two.

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3 years ago

How does the density of water change when: (a) it is heated from 0o

Radda [10]

Answer:

[b] it id heated from 4o

Explanation:

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3 years ago

A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting

rusak2 [61]

Answer:

The rate of change of the distance between the helicopter and yourself (in ft/s) after 5 s is $\sqrt{725}$ ft/ sec

Explanation:

Given:

h(t) = 25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec . 5 = 125 ft

x(5) = 10 ft/sec . 5 = 50 ft

Now we can calculate the distance between the person and the helicopter by using the Pythagorean theorem

$D(t) = \sqrt{h^2 + x^2}$

Lets find the derivative of distance with respect to time

$\frac{dD}{dt} (t) = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}$

Substituting the values of h(t) and x(t) and simplifying we get,

$\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}$

$\frac{dh}{dt} = 25ft/sec$

$\frac{dx}{dt} = 10 ft/sec$

$\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}$ = $\frac{725}{\sqrt{725}}$ = $\sqrt{725}$ ft / sec

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3 years ago

Define moment of momentum. at which condition is it's magnitude zero?

ololo11 [35]

Let's start with the concept of momentum. What is it? Linear momentum in physics is mathematically written as a product of mass and velocity of an object. Now let us suppose a body of mass m is moving in an inertial frame of reference with velocity v. Consider the fact that no external force is acting on the system. The momentum of this body is given by mv, where m is the mass and v is its velocity. In case of simple real world problems not delving into the realms of relativity, mass is a conserved quantity and it cannot be zero. Hence the velocity of the body must be zero and hence the momentum.

However, photons are considered to have a rest mass zero.

However note the point carefully "rest mass". A body in motion cannot have mass to be zero.

- BRAINLIEST answerer ❤️

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3 years ago