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3 years ago

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Physics

1 answer:

Setler79 [48]3 years ago

5 0

He must throw the device AWAY from the ship.

Since momentum is conserved, that move will give HIM an equal amount of momentum TOWARDS the ship.

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Three students each hold basketballs with the same masses at varying heights. One basketball is held 2 feet above the ground. An

Advocard [28]

The Basketball with the greatest gravitational potential energy is : Basketball 4 feet above the ground ( c )

<u>Given data :</u>

masses = constant

H₁ = 2 ft

H₂ = 3 ft

H₃ = 4 ft

g = 9.81 m/s²

<h3><u>Procedure to determine the basketball with the greatest gravitational P.E </u></h3>

we will apply the equation below

Gravitational potential energy ( U ) = mgh

For ball 1

U = 2 * 9.81 = 19.62

For ball 2

U = 3 * 9.81 = 29.43

For ball 3

U = 4 * 9.81 = 39.24

From the calculations the basketball with the greatest gravitational potential energy is the basketball at 4ft above the ground

Learn more about gravitational potential energy : brainly.com/question/15896499

4 0

3 years ago

Mr. Stephenson drives his car from Dallas to Town X, a distance of 437 km. The trip takes 7.27 hours. What is the average speed

alexandr1967 [171]

Answer: S<span>peed = 60.11 miles per hour
</span>

To solve for speed or rate use the formula for speed, s = d/t which means speed equals distance divided by time.

<span>speed = distance/time</span>

3 0

3 years ago

Read 2 more answers

A woman can row a boat at 5.60 km/h in still water. (a) If she is crossing a river where the current is 2.80 km/h, in what direc

katrin2010 [14]

Answer:

a) θ=210°, b) t=1.155hr, c) t=1.333hr, d) t=1.333hr, e) θ=180° (straight across), f) t=1hr.

Explanation:

So, the very first thing we nee to do when solving this problem is draw a diagram that represents it. In the attached picture I show a diagram for each part of this problem.

part a)

So, for her to move in a direction directly opposite her starting point, the x-component of her velocity must be de same as the velocity of the river in the opposite direction. We can use this fact to find the angle we need. If we analize the triangle I drew in the diagram, we can ses that:

$cos \theta = \frac {V_{river}}{V_{boat}}$

When solving for theta, we get that:

$\theta =cos^{-1} ( \frac {V_{river}}{V_{boat}})$

so now we can substitute the corresponding values:

$\theta =cos^{-1} ( \frac {2.80km/hr}{5.60km/hr}})$

Which yields:

$\theta = 60^{o}$

but we are measuring the angle relative to the line perpendicular to the river, positive if down the river. So we need to subtract the angle from 270° so we get:

θ=270°-60°=210°

part b)

for part b, we need to find what the y-component for the velocity of the boat is for an angle of 210° as shown in the problem, so we get that:

$V_{y}=5.60km/hr*cos(210^{o})$

$V_{y}=-4.85km/hr$

The woman will head in a negative 5.60km distance from one side to the other, so we get that the time it takes her to go to the other side of the river is:

$t=\frac{y}{V_{y}}$

$t=\frac{5.60km}{4.85km/hr}=1.155hr$

part c)

In order to find the time it takes her to travel 2.80km down and up the river, we need to find the velocities she will have in both directions. First, down stream:

$V_{ds}=V_{river}+V{boat}$

$V_{ds}=2.80km/hr+5.60km/hr=8.40km/hr$

and now up stream:

$V_{us}=V_{boat}-V{river}$

$V_{us}=5.60km/hr-2.80km/hr=2.80km/hr$

Once we got these two velocities we will now need to find the time to take each trip:

time down stream:

$t_{ds}=\frac{x}{v_{ds}}$

$t_{ds}=\frac{2.80km}{8.40km/hr}=0.333hr$

and the time up stream:

$t_{us}=\frac{x}{v_{us}}$

$t_{us}=\frac{2.80km}{2,80km/hr}=1hr$

so the total time will be:

$t_{ds}+t_{us}=0.333hr+1hr=1.333hr$

d) the time it takes the boat to go upstream and then downstream for the same distance is the same as the time we got on part c, since both times will be the same but they will come in different order, but their sum will be just the same:

t=1.333hr

e) For her to cross the river faster, she must row in a 180° direction (this is in a direction straight accross the river) that way she will use all her velocity to move across the river. (Even though she will move a certain distance horizontally and will not reach a point opposite to the starting point.)

f) In order to find the time it takes her to get to the other side, we need to divide the distance into the velocity of the boat.

$t=\frac{d}{v_{boat}}$