A car traveling 35 km/hr accelerates to a speed of 45 km/hr in .25 hr. What is its acceleration

Can we see the back side of the moon from earth?

Olegator [25]

No. The moon always keeps the same side facing us. Its rotation and revolution periods are equal.

5 0

3 years ago

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A 1300-N crate rests on the floor. How much work is required to move it at constant speed (a)

kherson [118]

a) The work done is 920 J

b) The work done is 5200 J

Explanation:

a)

In this first part of the problem, the crate is moved horizontally at constant speed.

The work required in this case is given by

$W=Fd cos \theta$

where

F is the magnitude of the force applied

d is the displacement of the crate

$\theta$ is the angle between the direction of the force and of the displacement

Here the crate is moved at constant speed: this means that the acceleration of the crate is zero, and so according to Newton's second law, the net force on the crate is zero: this means that the force applied, F, must be equal to the force of friction (but in opposite direction), so

F = 230 N

The displacement is

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied horizontally. Therefore, the work done is

$W=(230)(4.0)(cos 0^{\circ})=920 J$

b)

In this case, the crate is moved vertically. The force that must be applied to lift the crate must be equal to the weight of the crate (in order to move it a constant speed), therefore

F = W = 1300 N

The displacement this time is again

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied vertically, and the crate is moved also vertically. Therefore, the work done on the crate this time is

$W=(1300)(4.0)(cos 0^{\circ})=5200 J$

Learn more about work:

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4 0

3 years ago

How many birds have tested positive for West Nile virus?

snow_lady [41]

I believe the last time the dead bird count was updated (12/16/16), there is a count of 1,350 dead birds. There is 1,350 dead birds from 33 countries have tested positive for WNV in 2016.

5 0

3 years ago

A bird is flying east at 5.2 kilometers/hour relative to the air. There's a crosswind blowing at 3.1 kilometers/hour toward the

alexandr402 [8]

Answer:

r=6.05km/hr

z=59.1 degree to the horizontal

Explanation:

A bird is flying east at 5.2 kilometers/hour relative to the air. There's a crosswind blowing at 3.1 kilometers/hour toward the south relative to the ground. What is the bird's velocity relative to the ground? State your answer to one decimal place

can be solved using pythagoras theorem

r^2=o^2+a^2

r^2=5.2^2+3.1^2

r^2=36.65

r=6.1km/hr is te birds velocity relative to the ground

tanz=5.2/3.1

z=tan^-1(5,2/3.1)

z=59.1 degree to the horizontal

7 0

3 years ago

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In the presence of ________, hydrogen peroxide will decompose into oxygen and water.

IrinaK [193]

Answer: Catalase enzyme

Explanation:

The catalase is an enzyme that is commonly found in the living organisms that are exposed to minute or high amount of oxygen or those in which aerobic respiration takes place.

This enzyme catalyzes the breakdown or decomposition of the hydrogen peroxide into oxygen and water. In humans and animals the catalase is present in liver, where it conducts the function of detoxifying the body by decomposing the toxins.

7 0

3 years ago