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KonstantinChe [14]

2 years ago

11

Since vectors always have positive magnitudes, the sum of two vectors must have a magnitude greater than the magnitude of either

one of them. O True O False

1 answer:

Natasha2012 [34]2 years ago

6 0

Answer:

False.

Explanation:

Yes the magnitude of a vector is always positive , but a vector consists of

magnitude

direction

when two vectors are added their direction may be opposite to each other For example-

$a=3i+3j$

$b=3i-6j$ ,

then their resultant

$r=b+a\\r=3i+3j+3i-6j\\r=6i-3j$

This resultant vector's x and y component equal to y and x component of vector b so its magnitude will be equal to magnitude of vector b.

Therefore, the resultant magnitude not necessary equal to the magnitude of either vector.

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Which statement accurately describes nutritional dietary supplements?

vladimir2022 [97]

Answer:

its b

Explanation:

7 0

2 years ago

an automobile is traveling 65km/h the brakes decelerate it at a rate of -6.0 m/s^2 how long will it take to stop the car?

joja [24]

Explanation:

It is given that,

Initial speed of the automobile, u = 65 km/hr =

Final speed of the automobile, v = 0

Deceleration of the automobile, $a=-6\ m/s^2$

We need to find the distance covered by the car as it comes to rest. It can be calculated using third equation of motion as :

$v^2-u^2=2ax$

$a=\dfrac{v^2-u^2}{2x}$

$a=\dfrac{0-(18.05)^2}{2\times (-6)}$

$a=27.15\ m/s^2$

So, the acceleration of the car is $27.15\ m/s^2$ . Hence, this is the required solution.

6 0

2 years ago

B. Complete the lists:

d1i1m1o1n [39]

Answer:

Things you should do for your family

help your parents
treat them kindly
listen and obey them
appreciate them for anything they do for you
talk softly

things you shouldn't

backanswering them
Disobey
And anything that's harsh or make it parents sad

6 0

2 years ago

A motorcycle daredevil plans to ride up a 2.0-m-high, 20° ramp, sail across a 10-m-wide pool filled with hungry crocodiles, and

il63 [147K]

Answer:

He becomes a croco-dile food

Explanation:

From the question we are told that

The height is h = 2.0 m

The angle is $\theta = 20^o$

The distance is $w = 10m$

The speed is $u = 11 m/s$

The coefficient of static friction is $\mu = 0.02$

At equilibrium the forces acting on the motorcycle are mathematically represented as

$ma = mgsin \theta + F_f$

where $F_f$ is the frictional force mathematically represented as

$F_f =\mu F_x =\mu mgcos \theta$

where $F_x$ is the horizontal component of the force

substituting into the equation

$ma = mgsin \theta + \mu mg cos \theta$

$ma =mg (sin \theta + \mu cos \theta )$

making a the subject of the formula

$a = g(sin \theta = \mu cos \theta )$

substituting values

$a = 9.8 (sin(20) + (0.02 ) cos (20 ))$

$= 3.54 m/s^2$

Applying " SOHCAHTOA" rule we mathematically evaluate that length of the ramp as

$sin \theta = \frac{h}{l}$

making $l$ the subject

$l = \frac{h}{sin \theta }$

substituting values

$l = \frac{2}{sin (20)}$

$l = 5.85m$

Apply Newton equation of motion we can mathematically evaluate the final velocity at the end of the ramp as

$v^2 =u^2 + 2 (-a)l$

The negative a means it is moving against gravity

substituting values

$v^2 = (11)^2 - 2(3.54) (5.85)$

$v= \sqrt{79.582}$

$= 8.92m/s$

The initial velocity at the beginning of the pool (end of ramp) is composed of two component which is

Initial velocity along the x-axis which is mathematically evaluated as

$v_x = vcos 20^o$

substituting values

$v_x = 8.92 * cos (20)$

$= 8.38 m/s$

Initial velocity along the y-axis which is mathematically evaluated as

$v_y = vsin\theta$

substituting values

$v_y = 8.90 sin (20)$

$= 3.05 m/s$

Now the motion through the pool in the vertical direction can mathematically modeled as

$y = y_o + u_yt + \frac{1}{2} a_y t^2$

where $y_o$ is the initial height,

$u_y$ is the initial velocity in the y-axis

$a_y$ is the initial acceleration in the y axis with a constant value of ( $g = 9.8 m/s^2$ )

at the y= 0 which is when the height above ground is zero

Substituting values

$0 = 2 + (3.05)t - 0.5 (9.8)t^2$

The negative sign is because the acceleration is moving against the motion

$-(4.9)t^2 + (2.79)t + 2m = 0$

Solving using quadratic formula

$\frac{-b \pm \sqrt{b^2 -4ac} }{2a}$

substituting values

$\frac{-3.05 \pm \sqrt{(3.05)^2 - 4(-4.9) * 2} }{2 *( -4.9)}$

$t = \frac{-3.05 + 6.9}{-9.8} \ or t = \frac{-3.05 - 6.9}{-9.8}$

$t = -0.39s \ or \ t = 1.02s$

since in this case time cannot be negative

$t = 1.02s$

At this time the position the motorcycle along the x-axis is mathematically evaluated as

$x = u_x t$

x $=8.38 *1.02$

$x =8.54m$

So from this value we can see that the motorcycle would not cross the pool as the position is less that the length of the pool

7 0

2 years ago

The reciprocal of frequency is

Colt1911 [192]

Frequency=1/T, where T is the time period.
Reciprocal of frequency = T or it can be written as T = 1/f, where f is frequency.

8 0

2 years ago