Physics, 28.09.2019 13:00, cobalt426

Aboat of mass 115 kg drifts along a river at a speed of 13 m/s to the east. what impulse is required to decrease the speed of the boat to 10 m/s to the east?

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Answers

M = 115 kg.

Final velocity, v = 10 m/s to the east

Initial Velocity, u = 13 m/s to the east

Impulse = m(v - u)

= 115*(10 - 13)

= 115*-3 = -345 kgm/s or -345 Ns

answered: cabr379

An impulse of $\boxed{345\text{ N}\cdot\text{s}}$ to the west is required to decrease the speed of the boat from $13\text{ m/s}$ east to $10\text{ m/s}$ east.

Further explanation:

When a force acted upon an object for a very small time, is called impulse. Force is a rate of change of momentum with respect to time. Therefore if momentum associated with an object is changed in a very short time, the force exerted on the object is called the impulse.

Given:

Mass of the boat is $115\text{ kg}$ .

Initial speed of the boat is $13\text{ m/s}$ to the east.

Final velocity of the boat is $10\text{ m/s}$ to the east.

Concept:

Let’s assume east direction as the positive direction of x axis.

Write the expression for impulse

$\begin{aligned}I&={{\vec F}_{{\text{avg}}}}\cdot\Delta t\\&=\Delta m\vec V\\\end{aligned}$

Here, is the impulse force, $\Delta m\vec V$ is the change of momentum, $\Delta t$ is the time and is the mass of the boat.

In the above expression is a constant, therefore above expression can be rewritten as

$I=m\cdot\Delta\vec V$ …… (1)

Here, $\Delta\vec V$ is the change in the velocity of the boat.

Write the expression for change in velocity

$\Delta\vec V={V_{\text{f}}}-{V_{\text{i}}}$ …… (2)

Here, ${V_{\text{f}}}$ is the final velocity of boat and ${V_{\text{i}}}$ is the initial velocity of the boat.

Substitute $13\text{ m/s}$ for ${V_{\text{i}}}$ and $10\text{ m/s}$ for ${V_{\text{f}}}$ in equation (2).

$\begin{aligned}\Delta \vec V&=\left( {10\,\hat i}\right)-\left( {13\,\hat i}\right)\\&=3\,\left({-\hat i}\right)\\\end{aligned}$

Substitute $3\,{\text{m/s}}\,\left( { - \hat i} \right)$ for $\Delta \vec V$ and $115\text{ kg}$ for in equation (1).

$\begin{aligned}I&=\left({115\,{\text{kg}}}\right)\left( {-3\,{\text{m/s}}\,\hat i}\right)\\&=345\,{\text{N.s}}\left({-\hat i} \right)\\\end{aligned}$

Here, indicate that the impulse acts in opposite of east direction.

Thus, an impulse of $\boxed{345\text{ N.s}}$ to the west is required to decrease the speed of the boat from $13\text{ m/s}$ east to $10\text{ m/s}$ east.

Learn More:

1. Calculate the net force on Earth due to Venus, mars and jupiter

2. The maximum force to be exerted on a wooden crate to move it with acceleration

3. Conservation of momentum during collision

Answer Details:

Grade: High School

Subject: Physics

Chapter: Force

Keywords:

Boat, mass, 115 kg, drifts, river, 13 m/s, 13 meter per second, east, impulse, decrease, speed, 10 m/s, 10 meter per second, 345 Ns, west, 3.45 times 10^2 Ns.

Aboat of mass 115 kg drifts along a river at a speed of 13 m/s to the east. what impulse is required

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the moon affects the earth gravitation ally, causing certain motions of that body and also producing tides in its ocean and atmosphere. the tidal wave in our atmosphere is, however, far too minute to be an effective cause in any known meteorological phenomenon.

explanation:

answered: Guest

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Aboat of mass 115 kg drifts along a river at a speed of 13 m/s to the east. what impulse is required...