Which statement about an object in motion is correct? Help

What do scientists use a scientific law for?

Sedbober [7]

They use Scientific Law to support theories made by people who work in the Scientific field.

8 0

3 years ago

The slope of the following graph represents

guajiro [1.7K]

Answer:

ok jsjajakaka you can come to me when you get home can you please send me the details of the day and I will be there at this time of year is the best way to get a hold of the guy who was the guy who was the guy who was the guy who was the guy who was the guy that was the only thing that was the case but I don't know if I can help you

4 0

3 years ago

An engine draws energy from a hot reservoir with a temperature of 1250 K and exhausts energy into a cold reservoir with a temper

bixtya [17]

Answer:

a. $P=18.61\ W$

b. $\eta_c=0.6976=69.76\%$

c. $\eta=0.4718=47.18\%$

Explanation:

Given:

temperature of the hotter reservoir, $T_H=1250\ K$

temperature of the colder reservoir, $T_C=378\ K$

heat absorbed by the engine, $Q_H=1.42\times 10^{5}\ J$

heat rejected to the cold reservoir, $Q_L=7.5\times 10^4\ J$

time duration of the energy transfer, $t=1\ hr=3600\ s$

Now the work done by the engine:

Using energy conservation,

$W=Q_H-Q_L$

$W=14.2\times 10^4-7.5\times 10^4$

$W=6.7\times 10^4\ J$

a.

Hence the power output:

$P=\frac{W}{t}$

$P=\frac{6.7\times 10^4}{3600}$

$P=18.61\ W$

b.

$\eta_c=1-\frac{T_L}{T_H}$

$\eta_c=1-\frac{378}{1250}$

$\eta_c=0.6976=69.76\%$

c.

now actual efficiency:

$\eta=\frac{W}{Q_H}$

$\eta=\frac{6.7\times 10^4}{1.42\times 10^{5}}$

$\eta=0.4718=47.18\%$

6 0

4 years ago

To view an interactive solution to a problem that is similar to this one, select Interactive Solution 7.24. A 0.0146-kg bullet i

Vinil7 [7]

Answer:

0.25223 seconds.

Explanation:

$m_1$ = Mass of bullet = 0.0146 kg

$m_2$ = Mass of block = 2.55 kg

v = Combined velocity

$u_1$ = Velocity of bullet = 816 m/s

g = Acceleration due to gravity = 9.81 m/s²

As linear momentum is conserved

$m_1u_1 + m_2u_2 =(m_1 + m_2)v$

Now $u_2=v$ as the block (with the bullet in it) reverses direction and rises,

$m_1u_1 + m_2v =(m_1 + m_2)v\\\Rightarrow m_1u_1=(m_1 + m_2)v-m_2v\\\Rightarrow 0.0146\times 816=(0.0146 + 2.55)v-(-2.55v)\\\Rightarrow 11.9136=2.2646v+2.55v\\\Rightarrow 11.9136=4.8146v\\\Rightarrow v=\frac{11.9136}{4.8146}\\\Rightarrow v=2.47447\ m/s$

Equation of motion

$v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{2.47447-0}{9.81}\\\Rightarrow t=0.25223\ s$

The time t is 0.25223 seconds.

3 0

3 years ago

House current is 120 volts. If a light bulb runs a current of 10 amps, what is the resistance?

nlexa [21]

Answer:

12 ohms

Explanation:

Ohm's Law tells the relationship between voltage, current, and resistance.

It can be written in three different ways, depending on which ones you know,

and which one you want to find.

Here's the one we need:

Resistance = (voltage) divided by (current)

= (120 V) / (10 Amp)

= 12 ohms .

6 0

3 years ago