Driving home from school one day, you spot a ball rolling out into the street (Figure 5-21). You brake for 1.20 s, slowing your 950-kg car from 16.0 m/s to 9.50 m/s.a) What was the average force exerted on your car during braking?
b) How far did you travel while braking?

Answers

Answer 1

Answer: a ) v = v o + a t ( the acceleration will be negative )
9.50 = 16.0 + a * 1.2
a * 1.2 = -16.0 + 9.50
a * 1.2 = - 6.5
a = - 6.5 : 1.2
a = - 5.4167 m/s²
F = m * a = 950 kg * 5.4167 m/s²
F = 5,145.8 N ( the average force exerted on a car during braking )
b ) d = v o - a t² / 2
d = 16.0 * 1.2 - ( 5.4167 * 1.2² / 2 ) =
= 19.20 - 3.90 = 15.30 m

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Cations have fewer _____ than _____.a. neutrons; protons
b. protons; neutrons
c. electrons; protons
d. protons; electrons

Answers

Answer:

C.Electrons,protons.

Explanation:

Cations:

When metal loos it electrons then it will form cations.

Ex: $Na^(+1)$

Anion:

When metal gain electron then it will from anions.

Ex: $F^(-1)$

So from above we can say that ,the cations have fewer electrons than protons.Protons is also called as positive charged ions and electron are also called negatively charge ions.

SO the option is C is correct.

Cations are positively charged ions. And for positive charged ions, it means the positive charges, protons, are more than the negative charges, the electrons.

Therefore Cations have fewer electrons than protons.

So the answer is: c. electrons; protons.

Force = 65 kg x 3 m/s =What is the answer?

What units do you use for your end result?

Answers

Answer:

multiply 65kg and 3m/s^2

to get 195kgm/s

or 195N

wait is that 3m/s or 3m/s^2?

A 0.5 kg ball is dropped from rest at a point 1.2m above the floor. The ball rebounds straight upward to a height of 0.7m. What are the magnitude and direction of the impulse of the net force applied to the ball during the collision with the floor.

Answers

Answer:

4.281 kgm/s upward

Explanation:

Impulse:This can be defined product of force and time. The S.I unit of impulse is Ns.

From Newton's second law of motion,

Impulse = Change in momentum.

I = mΔv....................... Equation 1.

Where m = mass of the ball, Δv = change in velocity of the ball

and Δv = v -u

Where u = velocity of the ball before it hit the floor, v = velocity of the ball after if hit the floor

I = m(v-u) -------------- Equation 2

But

the initial kinetic energy of the ball = potential energy at the initial height (1.2 m above)

1/2mu² = mgh₁

Where h₁ = initial height. or height of the ball before collision

making u the subject of the equation,

u = √(2gh₁)........................ Equation 3

Where h₁ = 1.2 m g = 9.81 m/s²

Substitute into equation 3

u = √(2×1.2×9.81)

u =√(23.544)

u = -4.852 m/s.

Note: u is negative because the ball was moving downward at the first instance.

Similarly,

v = √(2gh₂)............................. Equation 3

h₂ = height of the ball after collision

Given: h₂ = 0.7 m, g = 9.81 m/s²

Substitute into equation

v = √(2×9.81×0.7)

v = √13.734

v = 3.71 m/s.

Also given: m = 0.5 kg,

Substituting into equation 2

I = 0.5(3.71-(4.852)

I = 0.5(8.562)

I = 4.281 kgm/s. Upward.

Thus the impulse = 4.281 kgm/s upward

5. Projectile A with mass m is launched at an angle of 20° above the horizontal with a speed v0. Projectile B also with mass m is launched from the same location at an angle of 70° above the horizontal, also with speed v0. Thus, both projectiles have the same initial total energy. a. Which projectile has a larger speed when it hits the ground or do they have the same speed? Explain using energy. b. Which projectile reaches a greater height? Given that both projectiles have the same initial energy, how is this possible?

Answers

Answer:

a) They both have the same final speed.

b) Projectile B reaches a greater height

Explanation:

The initial total energy of both projectiles is the same, and since the initial height is zero, that initial energy is entirely kinetic energy:

$E_0=K_0=(1)/(2)mv_0^(2)$

Now, when the projectiles are going to reach the ground, their height also becomes zero, so the final energy is also entirely kinetic energy:

$E_f=K_f=(1)/(2)mv_f^(2)$

As stated in the conservation of mechanical energy, the final total energy has to be equal to the initial total energy, and then:

$E_0=E_f\n \n (1)/(2)mv_0^(2)=(1)/(2)mv_f^(2)\n\n\implies v_0=v_f$

Finally, since the initial speed is the same for both projectiles, they have the same speed when they hit the ground (a).

Next, we know that the height reached by a projectile depends only of their initial vertical velocity, nor their horizontal one. So, the projectile with the highest initial vertical velocity has to reach a greater height. We use trigonometry to calculate that:

$v_0_A_y=v_0\sin20\°=0.34v_0\n\nv_0_B_y=v_0\sin70\°=0.93v_0$

It means that projectile B has a higher initial vertical velocity, so it reaches a greater height (b).

This is possible because some of the kinetic energy of both projectiles is never transformed to gravitational potential energy (because is related to the horizontal velocity) and this amount of kinetic energy depends on the angle at which the projectile is launched. As their potential energies at the highest points are different, their maximum heights are, too.

What is a main sequence star?
definition please:)

Answers

Any star that is fusing hydrogen in its core and maintains a stable equilibrium between the inward pressure from gravity and the outward pressure from core nuclear fusion is called the main sequence star.

The main sequence is a continuous and recognisable band of stars in astronomy that may be seen on maps of stellar colour against brightness.

A star produces thermal energy in its dense core area by nuclear fusing hydrogen into helium after condensation and ignition. The star's location on the main sequence at this moment in its existence is mostly based on its mass, but also on factors like its age and chemical makeup.

Main-sequence stars' cores are in a state of hydrostatic equilibrium, where the inward pressure of gravitational collapse from the surrounding layers balances the outward heat pressure of the hot core.

To learn more about main sequence star, click:

brainly.com/question/1966525

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The main sequence star definition is A main sequence star is any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward. I will also put a picture of the star life cycle linked on my answer hope this helps :)

PLEASE HELP ASAP!!!!!