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Sergeeva-Olga [200]
2 years ago
15

Trafegando por uma avenida com velocidade constante de 54km/h, num dado instante, o motorista percebe o sinal vermelho à sua fre

nte e pisa no freio até que, depois de 5 s, o automóvel para. Determine a aceleração escalar média do carro nesse intervalo de tempo em Km/h dividido por s e em m/s²
Physics
1 answer:
Furkat [3]2 years ago
5 0

Answer:

The acceleration is - 3 m/s2.

Explanation:

initial speed, u = 54 km/h = 15 m/s

final speed, v = 0

time, t = 5 s

Let the acceleration is a.

use first equation of motion

v = u + at

0 = 15 + a x 5

a = - 3 m/s2

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A power boat pulls a water skier 2.6 km maintaining a
Luba_88 [7]

Answer:

W = 650 [kJ]

Explanation:

The definition of work is denoted by the product of force by the distance traveled by the body, this distance traveled corresponds to the direction of the force.

In this case we have:

d = distance = 2.6[km] = 2600 [m]

F = force = 250 [N]

W = F*d = 250 * 2600 = 650000 [J] or 650 [kJ]

7 0
3 years ago
Use the Bohr model to address this question. When a hydrogen atom makes a transition from the 5 th energy level to the 2nd, coun
iris [78.8K]

Answer:

A. 2.82 eV

B. 439nm

C. 59.5 angstroms

Explanation:

A. To calculate the energy of the photon emitted you use the following formula:

E_{n1,n2}=-13.4(\frac{1}{n_2^2}-\frac{1}{n_1^2})     (1)

n1: final state = 5

n2: initial state = 2

Where the energy is electron volts. You replace the values of n1 and n2 in the equation (1):

E_{5,2}=-13.6(\frac{1}{5^2}-\frac{1}{2^2})=2.82eV

B. The energy of the emitted photon is given by the following formula:

E=h\frac{c}{\lambda}   (2)

h: Planck's constant = 6.62*10^{-34} kgm^2/s

c: speed of light = 3*10^8 m/s

λ: wavelength of the photon

You first convert the energy from eV to J:

2.82eV*\frac{1J}{6.242*10^{18}eV}=4.517*10^{-19}J

Next, you use the equation (2) and solve for λ:

\lambda=\frac{hc}{E}=\frac{(6.62*10^{-34} kg m^2/s)(3*10^8m/s)}{4.517*10^{-19}J}=4.39*10^{-7}m=439*10^{-9}m=439nm

C. The radius of the orbit is given by:

r_n=n^2a_o   (3)

where ao is the Bohr's radius = 2.380 Angstroms

You use the equation (3) with n=5:

r_5=5^2(2.380)=59.5

hence, the radius of the atom in its 5-th state is 59.5 anstrongs

8 0
3 years ago
A wave with a greater amplitude will transfer . . . . \
BabaBlast [244]

less mass is more mass but less energy in more mass. less mass has more energy

6 0
3 years ago
Which has the lowest heat capacity? (values of heat capacities and calculations are unnecessary).
Brrunno [24]

The correct answer is Metals.

Generally, the specific heat of metals is low. Very high specific heat exists in water.A physical feature of matter known as heat capacity or thermal capacity is the quantity of heat that must be applied to an object in order to cause a unit change in temperature. Heat capacity is measured in joules per kelvin (J/K), the SI unit. A broad property is heat capacity. Use the following equation to determine heat capacity: heat capacity = E / T, where E is the quantity of delivered heat energy and T is the change in temperature. The formula would be as follows, for instance, if it takes 2,000 Joules of energy to raise a block's temperature by 5 degrees Celsius: 2,000 Joules per °C is the heat capacity.

Learn more about heat capacity here :-

brainly.com/question/13499849

#SPJ4

5 0
1 year ago
Ava runs track and field and is a long-distance runner. She has a big race coming up and needs to eat food that will provide her
Tema [17]
A salad most likely
4 0
3 years ago
Read 2 more answers
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