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AnnyKZ [126]
3 years ago
13

An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train . When the engineer first

sees the car, the locomotive is 110 m from the crossing and its speed is 21 m/s . If the engineer's reaction time is 0.6 s, what should be the magnitude of the minimum de celeration to avoid an accident ? Answer in units of m/s^ 2
Physics
1 answer:
8_murik_8 [283]3 years ago
4 0

Answer:

Explanation:

distance traveled during reaction time

d = vt = 21(0.6) = 12.6 m

distance remaining 110 - 12.6 = 97.4 m

Assuming we want zero speed in 97.4 m using constant acceleration.

a = (0² - 21²) / 2(97.4) = - 2.2638603...

the negative value indicates acceleration opposes initial velocity.

magnitude is

a = 2.3 m/s²

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A plane leaves the airport in Galisteo and flies 170 km at 68.0° east of north; then it changes direction to fly 230 km at 36.0°
luda_lava [24]

Answer:

The direction will be 84.86^\circ and the distance 250.75km.

Explanation:

Let's say A is the displacement vector which represents the first 170km and B the one for the next 230km. Then the components of these vector will be:

A_x=170cos(68^{\circ})\\ A_y=170sin(68^\circ)\\\\B_x=230cos(-36^\circ)\\B_y=230sin(-36^\circ)

The vector which point from the origin to the final position of the plane will be R=A+B. We sum components on <em>x </em>and <em>y </em>independetly (vector property):

R_x=A_x+B_x=170cos(68^{\circ})+230cos(-36^\circ)=63.68km+186.07km=249.75km

R_y=A_y+B_y=170sin(68^\circ)+230sin(-36^\circ)=157.62km-135.19km=22.43km

If \theta is the direction of R then:

tan(\theta )=\frac{R_x}{R_y} ⇒ \theta = arctan(\frac{R_x}{R_y}) ⇒ \theta = 84.86^\circ.

The distance will be given by the magnitud of the vector R:

R=\sqrt{R_x^2 + R_y^2} ⇒ R=\sqrt{R_x^2 + R_y^2} = 250.75.

4 0
3 years ago
A skateboarder traveling with an initial velocity 9.0 meters per second,
meriva

Answer:

25m/s

Steps:

<em> First, The equation v= u + a * t shows us what we need to find, (the finale velocity). </em>

<em />

Second, we substitute the values given:

v= 9m/s + 4m/s2 * 4s

Last, We calculate the values:

Multiply 4m/s2 * 4s = 16m/s  

Add 9m/s + 16m/s

<u></u>

<u>Answer:  25m/s</u>

Hope this helps :)

4 0
3 years ago
What do you need to know to establish motion
avanturin [10]

Answer:

An object is in motion if it changes position relative to a reference point.

Explanation:

7 0
2 years ago
A floating ice block is pushed through a displacement d = (13.5 m)i + (-14.3 m)j along a straight embankment by rushing water, w
fredd [130]

To solve this problem, we are going to use the formula for work which is Fd where x and y are measured separately.

 

X direction: W = 13.5 x 230 = 3105 Joules

Y direction: W = -14.3 x -165 = 2360 Joules

So the total work is getting the sum of the two: 3105 + 2360 = 5465 Joules

7 0
3 years ago
A B-52 bomber jet flies at a horizontal velocity of 286.2 m/s and at an altitude of 7500 m above the ground.
kykrilka [37]

Answer:

you need to divide 7500/286.2

3 0
2 years ago
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