Calculate the gravitational force of 2 masses of 131 kg and 145 kg if they are 5.2 m apart.

Convert 70 mi/h to m/s. 1 mi = 1609 m. Answer in units of m/s. Plz help me now

melisa1 [442]

Answer:

70mi/h

1mile =1609 meters

1hour=3600 seconds

So,

70×1609/3600

112,630/3600

31.286 m/s

Hope this helps you

6 0

4 years ago

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.

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

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

so

t= 1hr

4 0

4 years ago

Read 2 more answers

1: A car traveling at 10 m acceleration uniformly at 2 m. Calculate its velocity after5 s.

s344n2d4d5 [400]

Answer:

20 m/s

Explanation:

v = u + at

v: final velocity

u: initial velocity

a: acceleration

t: time

v = 10 + 2(5)

v = 10 + 10

v = 20 m/s

4 0

3 years ago

Two plane waves of the same frequency and with vibrations in the z-direction are given by c (y, t) = (2 cm) cos a p 4 cm y - 20

My name is Ann [436]

The resultant wave at point (5, 2) is Ψ = 5.99 cos [ 7.15 - (20/s) t]

What are the plane waves:

A plane wave is a special case of wave or field: whose value, at any moment, is constant through any plane that is perpendicular to a fixed direction in space.
plane waves are free-space modes.

Here,

Two plane waves are given:

c (5, t) = 4 cos [(8π/3) - (20/s) t]

c (2, t) = 2 cos [(3π/2) - (20/s) t]

now, the waves as imaginary exponentials,

separating the spatial parts, and then adding them together

we get The resultant:

Ψ = [ 4 sin (8π/3) + 2 sin (3π/2) ]^2 + [ 4 cos(8/3 π) + 2 cos(3/2π) ]^2

Ψ = 5.99 tan(a) = 0.747/ 5.95

a = 7.15

Ψ = 5.99 cos [ 7.15 - (20/s) t]

hence,

The resultant wave is Ψ = 5.99 cos [ 7.15 - (20/s) t]

Learn more about Resultant wave here:

brainly.com/question/1190546

#SPJ4

Your question is incomplete, but most probably the full question was:

Two plane waves with the same frequency and with vibrations (measured by Psi) in the z-direction are given by c (x, t) = (4cm.) cos [pi/3cm. x - 20/s t + pi] c (y, t) = (2cm.) cos[pi/4cm. y - 20/s t + pi]

Express the waves as imaginary exponentials, separate the spatial parts, and add them together using a phasor diagram to find the resultant at the point x = 5cm. y = 2cm

4 0

2 years ago

What do I need to think in my mind when I hear about electric lines of forces ?

anzhelika [568]

Just ignore why do u care

3 0

3 years ago