What do i do for #17

A very smart 3-year-old child is given a wagon for her birthday. She refuses to use it. "After all," she says, "Newton's third l

natita [175]

Answer:

Explanation:

She's correct but doesn't mean the wagon cannot put into motion. The force that she applied on the wagon, according to Newton's 2nd law, would have generated an acceleration, which translates into motion. The reaction force the wagon applies on her due to Newton's 3rd law, would not hinder its own motion.

5 0

2 years ago

A projectile is shot directly away from Earth's surface. Neglect the rotation of the Earth. What multiple of Earth's radius RE g

7nadin3 [17]

Answer:

(a) r = 1.062·R $_E$ = $\frac{531}{500} R_E$

(b) r = $\frac{33}{25} R_E$

(c) Zero

Explanation:

Here we have escape velocity v $_e$ given by

$v_e =\sqrt{\frac{2GM}{R_E} }$ and the maximum height given by

$\frac{1}{2} v^2-\frac{GM}{R_E} = -\frac{GM}{r}$

Therefore, when the initial speed is 0.241v $_e$ we have

v = $0.241\times \sqrt{\frac{2GM}{R_E} }$ so that;

v² = $0.058081\times {\frac{2GM}{R_E} }$

v² = ${\frac{0.116162\times GM}{R_E} }$

$\frac{1}{2} v^2-\frac{GM}{R_E} = -\frac{GM}{r}$ is then

$\frac{1}{2} {\frac{0.116162\times GM}{R_E} }-\frac{GM}{R_E} = -\frac{GM}{r}$

Which gives

$-\frac{0.941919}{R_E} = -\frac{1}{r}$ or

r = 1.062·R $_E$

(b) Here we have

$K_i = 0.241\times \frac{1}{2} \times m \times v_e^2 = 0.241\times \frac{1}{2} \times m \times \frac{2GM}{R_E} = \frac{0.241mGM}{R_E}$

Therefore we put $\frac{0.241GM}{R_E}$ in the maximum height equation to get

$\frac{0.241}{R_E} -\frac{1}{R_E} =-\frac{1}{r}$

From which we get

r = 1.32·R $_E$

(c) The we have the least initial mechanical energy, ME given by

ME = KE - PE

Where the KE = PE required to leave the earth we have

ME = KE - KE = 0

The least initial mechanical energy to leave the earth is zero.

3 0

2 years ago

Read 2 more answers

A wagon is accelerating down a hill. Which statement is true?

Ira Lisetskai [31]

Potential energy decreases and kinetic energy increases.

Potential energy is related to the height, since the wagon is going downhill, height decreases and potential energy decreases.

Kinetic energy is related to the speed, since the wagon is speeding up, kinetic energy increases.

3 0

2 years ago

A woman of mass 50 kg is swimming with a velocity of 1.6 m/s. If she stops stroking and glides to a stop in the water, what is t

Snezhnost [94]

Answer:

Impulse of force = -80 Ns

Explanation:

Given the following data;

Mass = 50kg

Initial velocity = 1.6m/s

Since she glides to a stop, her final velocity equals to zero (0).

Now, we would find the change in velocity.

$Change \; in \; velocity = final \; velocity - initial \; velocity$

Substituting into the equation above;

Change in velocity = 0 - 1.6 = 1.6m/s

$Impulse \; of \; force = mass * change \; in \; velocity$

Substituting into the equation, we have;

$Impulse \; of \; force = 50 * -1.6$

Impulse of force = -80 Ns

Therefore, the impulse of the force that stops her is -80 Newton-seconds and it has a negative value because it is working in an opposite direction, thus, bringing her to a stop.

5 0

2 years ago

Explain whether demand is likely to be elastic or inelastic for Big Macs. A. Elastic comma since many other fast food items coul

anyanavicka [17]

Answer:

A - elastic since many other fast food items could be considered close substitutes.

Explanation:

The price elasticity of demand is how much the demand of the Big Macs will change due to a 1% change in price. Should the elasticity be greater than 1, the Big Macs will be elastic. Should it be less than 1, the Big Macs are inelastic.

Demand elasticity is calculated as the percentage change in quantity demanded divided by a percentage change in price.

Since Big Macs are (i) a luxury good, and (ii) have close substitutes (other burgers available at McDonalds and other fast food stores), we will say their elasticity is greater than 1.

This means that the demand of Big Macs will change due to a 1% increase in price due to the presence of close substitutes.

3 0

2 years ago