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3 years ago

If the net work done on an object is positive, what can you conclude about the object's motion?

Physics

1 answer:

ki77a [65]3 years ago

3 0

Since there is a positive work on an object, this directly indicates that there is an increase in Energy on the body.

Work can be expressed in terms of Force and distance as

W = Fd

Where,

F = Force

d = Distance

The force in turn is a description of how mass accelerates according to Newton's second law, that is

F = ma

The mass (m) remains constant, but the acceleration (a) is constant, which implies directly that there is a gradual change in the velocity of the object.

Therefore the correct answer is: <em>The object is speeding up.</em>

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You drop a stone down off a bridge. You are able to count to 4.0 seconds when it finally hits the water. How high is the bridge?

mart [117]

Answer:

The height of the bridge is 78.4 m.

Explanation:

Given;

time of the stone motion off the bridge, t = 4.0 s

acceleration due to gravity, g = 9.8 m/s²

The height of the bridge is given by;

h = ut + ¹/₂gt²

where;

u is the initial velocity of the stone, u = 0

h = ¹/₂gt²

h = ¹/₂(9.8)(4)²

h = 78.4 m

Therefore, the height of the bridge is 78.4 m.

7 0

3 years ago

What is the proportionality between pressure and temperature, and the proportionality between atmospheric pressure and tempratur

Alborosie

According to Ideal gasTo solve this problem, the fastest relationship allows us to observe the proportionality between the two variables would be the one expressed in the ideal gas equation, which is

$PV= NRT$

Here

P = Pressure

V = Volume

N = Number of moles

R = Gas constant

T = Temperature

We can see that the pressure is proportional to the temperature, then

$P \propto T$

This relationship can be extrapolated to all the scenarios in which these two variables are related. As the pressure increases the temperature increases. The same goes for the pressure in the atmosphere, for which an increase in this will generate an increase in temperature. This variable can be observed in areas of different altitude. At higher altitude lower atmospheric pressure and lower temperature.

6 0

3 years ago

How many amps of current are there in a system with 12 volts and 6 ohms?

Gemiola [76]

V = IR
I = V/R
I = 12/6
I = 2 amps

7 0

3 years ago

Read 2 more answers

A child whose weight is 235 N slides down a 4.90 m playground slide that makes an angle of 37.0° with the horizontal. The coeffi

Basile [38]

Answer:

Explanation:

a) First, let's calculate the value of the Friction force, which is given by the formula:

Ff = u*W

As the Friction force has an X component, it would be:

Ff = u*m*g*cosФ

Where m*g is the weight of the child.

Solving for Ff:

Ff = 0.051 * 235cos37 = 9.57 N

Now, to get the energy transferred to thermal energy (or heat) we need to get the Work done, so:

Wf = Ff * d

Wf = 9.57 * 4.9 = 46.9 J

b) We need to get the downslope component of the child weight, which is:

Wy = 235sin37 = 141.43 N

As you can imagine, the gravity also does work, so:

Wg = Wy * d

Wg = 141.43 * 4.9 = 693 J

Now, let's get the kinetic energy, which can be obtained by this expression:

ΔKe = Wg - Wf

ΔKe = 693 - 46.9 = 646.1 J

The formula for kinetic energy is:

Ke = 1/2 m*V^2

We have the innitial speed which is 0.355 m/s, and the mass can be obtained by m*g so:

Fw= m*g ----> m = Fw/g

m = 235 / 9.8 = 23.97 kg

so the innitial energy is:

Ke = 1/2 * 23.97 * (0.355)^2

Ke = 1.51 J

This could be Ke1, so to get Ke2:

ΔKe = Ke2 - Ke1

Ke2 = Δke + Ke1

Ke2 = 646.1 + 1.51 = 647,61 J

Finally, the speed at the bottom would be:

v = √2Ke/m

v = √2*647.61/23.97

v = 7.35 m/s

7 0

4 years ago

If a book has a a mass of 2 kg, how much does the book weigh?

Inessa05 [86]

Answer:

A. 20 N

Explanation:

Weight of the book = mass × acceleration due to gravity

= 2 × 10

= 20 N

6 0

3 years ago

Read 2 more answers