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sergij07 [2.7K]

3 years ago

5

Help me solve this. Someone help me pleeeaaaseee

1 answer:

White raven [17]3 years ago

6 0

dddddddddddddddddddddddddddfghjk

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A bird flies 3.6 km due west and then 1.8 km due north. Another bird flies 1.8 km due west and 3.6 km due north. What is the ang

kondor19780726 [428]

Define unit vectors as follows:
$\hat{i}$ is in the eastern direction.
$\hat{j}$ is in the northern direction.

The position of the first bird is
$\vec{a} = -3.6 \, \hat{i} + 1.8 \, \hat{j}$

The position of the second bird is
$\vec{b} = - 1.8 \, \hat{i} + 3.6 \, \hat{j}$

Let θ = the angle between the net displacement vector for the two birds.
By definition,
$\vec{a} . \vec{b} = |a| |b| cos\theta \\\\ \theta = cos^{-1} ( \frac{\vec{a}.\vec{b}}{|a||b|} )$

$\vec{a}.\vec{b} = (-3.6)(-1.8)+(3.6)(1.8) = 12.96$
$|a| = \sqrt{3.24+12.96} =4.025$
Similarly,
|b| = 4.025

Therefore
$\theta = cos^{-1} \frac{12.96}{4.025^{2}} =36.9^{o}$

Answer: 36.9°

5 0

3 years ago

A 4.0-m-diameter playground merry-go-round, with a moment of inertia of

HACTEHA [7]

Answer:

$7.1$ ms⁻¹

Explanation:

$d$ = diameter of merry-go-round = 4 m

$r$ = radius of merry-go-round = $\frac{d}{2}$ = $\frac{4}{2}$ = 2 m

$I$ = moment of inertia = 500 kgm²

$w_{i}$ = angular velocity of merry-go-round before ryan jumps = 2.0 rad/s

$w_{f}$ = angular velocity of merry-go-round after ryan jumps = 0 rad/s

$v$ = velocity of ryan before jumping onto the merry-go-round

$m$ = mass of ryan = 70 kg

Using conservation of angular momentum

$Iw_{i} - m v r = (I + mr^{2})w_{f}$

$(500)(2.0) - (70) v (2) = (I + mr^{2})(0)$

$1000 = 140 v$

$v = 7.1$ ms⁻¹

5 0

3 years ago

A 6 m long, uniform ladder leans against a frictionless wall and makes an angle of 74.3 ◦ with the floor. The ladder has a mass

olganol [36]

Answer: µ=0.205

Explanation:

The horizontal forces acting on the ladder are the friction(f) at the floor and the normal force (Fw) at the wall. For horizontal equilibrium,

f=Fw

The sum of the moments about the base of the ladder Is 0

ΣM = 0 = Fw*L*sin74.3º - (25.8kg*(L/2) + 67.08kg*0.82L)*cos74.3º*9.8m/s²

Note that it doesn't matter WHAT the length of the ladder is -- it cancels.

Solve this for Fw.

0= 0.9637FwL - (67.91L)2.652

Fw=180.1/0.9637

Fw=186.87N

f=186.81N

Since Fw=f

We know Fw, so we know f.

But f = µ*Fn

where Fn is the normal force at the floor --

Fn = (25.8 + 67.08)kg * 9.8m/s² =

910.22N

so

µ = f / Fn

186.81/910.22

µ= 0.205

4 0

3 years ago

What is the acceleration of the object?<br> m/s²

Orlov [11]

Answer:

-2.5m/s^2

Explanation:

10-40/12-0=-2.5

7 0

2 years ago

What type of mage can never be formed by a converging lens?

Irina18 [472]

Answer: Real image

Explanation:

converging lens will only produce a real image if the object is located beyond the focal point (i.e., more than one focal length away).

4 0

4 years ago