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3 years ago

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A truck filled with supplies sets out across the country at 9 A.M. It is traveling at a constant speed of 80.0 km/h. Two hours l

ater, a train starts out from the same location with similar supplies going to the same destination. The train travels at a constant speed of 110 km/h.

1 answer:

liberstina [14]3 years ago

5 0

Answer:

At 11 AM, the train is a constant speed of 110 km/h. when the truck is 160 ahead. When they meet, it will be 2 PM

Explanation:

At the train's first hour he moved to 110 km. The truck is at 160 km. The second hour includes train at 220 km, with truck at 240. At 2 PM, they are at the same place.

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Suppose a police officer is 1/2 mile south of an intersection, driving north towards the intersection at 40 mph. At the same tim

blagie [28]

Answer:

75.36 mph

Explanation:

The distance between the other car and the intersection is,

$x=x_{0}+V t \\ x=\frac{1}{2}+V t$

The distance between the police car and the intersection is,

$y=y_{0}+V t$

$y=\frac{1}{2}-40 t$

(Negative sign indicates that he is moving towards the intersection)

Therefore the distance between them is given by,

$z^{2}=x^{2}+y^{2}(\text { Using Phythogorous theorem })$

$z^{2}=\left(\frac{1}{2}+V t\right)^{2}+\left(\frac{1}{2}-40 t\right)^{2} \ldots \ldots \ldots(1)$

The rate of change is,

$2 z \frac{d z}{d t}=2\left(\frac{1}{2}+V t\right) V+2\left(\frac{1}{2}-40 t\right)(-40)$

$2 z \frac{d z}{d t}=V+2 V^{2} t-40+3200 t \ldots \ldots \ldots$

Now finding $z$ when $t=0,$ from (1) we have

$z^{2}=\left(\frac{1}{2}+V(0)\right)^{2}+\left(\frac{1}{2}-40(0)\right)^{2}$

$z^{2}=\frac{1}{4}+\frac{1}{4}=\frac{1}{2} \\ z=\sqrt{\frac{1}{2}} \approx 0.7071$

The officer's radar gun indicates 25 mph pointed at the other car then, $\frac{d z}{d t}=25$ when $t=0,$ from

From (2) we get

$2(0.7071)(25)=V+2 V^{2}(0)-40+3200(0)$

$2(0.7071)(25)=V+2 V^{2}(0)-40$

$35.36=V-40$

$V=35.36+40=75.36$

Hence the speed of the car is $75.36 mph$

7 0

3 years ago

A(n) 0.5 kg soccer ball approaches a player horizontally with a speed of 10.6 m/s. The player illegally strikes the ball with he

Llana [10]

Answer: - 25.2 kgm/s

Explanation: The mass of the ball is 0.5kg, and the initial velocity = 10.6m/s.

The final velocity is in opposite direction of the initial hence final velocity (v) = - 19.9 m/s

Impulse = change in momentum = final momentum - initial momentum.

Final momentum = mass × final velocity

Final momentum = - 19.9 × 0.5

Final momentum = - 9.95 kgm/s

Initial momentum = mass × initial velocity

Initial momentum = 0.5 × 10.6 = 5.3kgm/s

Change in momentum = final momentum - initial momentum = - 19.9 - 5.3

Change in momentum = - 25.2 kgm/s

The negative sign implies that the change in momentum is the opposite direction relative to the first.

6 0

3 years ago

A child is riding a merry-go-round that has an instantaneous angular speed of 12 rpm. If a constant friction torque of 12.5 Nm i

sammy [17]

Answer:

$-0.25 rad/s^2$

Explanation:

The equivalent of Newton's second law for rotational motions is:

$\tau = I \alpha$

where

$\tau$ is the net torque applied to the object

I is the moment of inertia

$\alpha$ is the angular acceleration

In this problem we have:

$\tau = -12.5 Nm$ (net torque, with a negative sign since it is a friction torque, so it acts in the opposite direction as the motion)

$I=50.0 kg m^2$ is the moment of inertia

Solving for $\alpha$ , we find the angular acceleration:

$\alpha = \frac{\tau}{I}=\frac{-12.5 Nm}{50.0 kg m^2}=-0.25 rad/s^2$

3 0

3 years ago

plz help me with this, I really need this pleaseee help!! I’ll give brainlist!!! Please help ( crying emoji ) :(

snow_tiger [21]

Soory i think multiple of velocity and angle

6 0

2 years ago

What level of intensity is playing golf while pulling or carrying a set of clubs?

Nuetrik [128]

Answer:

It would be considered Moderate intensity.

5 0

3 years ago