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Lera25 [3.4K]
3 years ago
15

Could I please get some help on this question I don’t understand .

Physics
1 answer:
Oksana_A [137]3 years ago
5 0

Answer:

12.5 m/s

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 0 m/s

Height (h) = 8 m

Final velocity (v) at 8 m above the lowest point =?

NOTE: Acceleration due to gravity (g) = 9.8 m/s²

The velocity of the roller coaster at 8 m above the lowest point can be obtained as follow:

v² = u² + 2gh

v² = 0² + (2 × 9.8 × 8)

v² = 0 + 156.8

v² = 156.8

Take the square root of both side

v = √156.8

v = 12.5 m/s

Therefore, the velocity of the roller coaster at 8 m above the lowest point is 12.5 m/s.

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A carpenter is driving a 15.0-g steel nail into a board. His 1.00-kg hammer is moving at 8.50 m/s when it strikes the nail. Half
bekas [8.4K]

Answer: The increase in temperature of the nail after the three blows is 8.0636 Kelvins. The correct option is (d).

Explanation:

Kinetic energy of the hammer ,K.E.=

\frac{1}{2}mv^2=\frac{1}{2}1.00 kg\times (8.50 m/s)^2=36.125 J

Half of the kinetic energy of the hammer is transformed into heat in the nail.

Energy transferred to the nail in one blow =

\frac{1}{2}K.E.=\frac{1}{2}\times 36.125 J=18.0625 J

Total energy transferred after 3 blows,Q =3\times 18.0625 J=54.1875 J

Mass of the nail = 15 g = 0.015 kg

Change in temperature =\Delta T

Specif heat of the steel = c = 448 J/kg K

Q=mc\Delta T

54.1875 J=0.015 kg\times 448 J/kg K\times \Delta T

\Delta T=8.0636 K\approx 8.1 K

The increase in temperature of the nail after the three blows is 8.1  Kelvins.Hence, correct option is (d).

4 0
3 years ago
In an automobile collision, a 44-kilogram passenger moving at 15 meters per second is brought to rest by an air bag during a 0.1
const2013 [10]

Answer:

6,600N

Explanation:

According to second law of motion, Force = mass × acceleration

If acceleration = change in velocity/time = 15/0.10

Acceleration = 150m/s²

Given mass = 44kg

Force = 44× 150

Force = 6,600N

Magnitude of the average force exerted on the passenger during this time is 6,600N

8 0
3 years ago
How much heat energy (in megajoules) is needed to convert 7 kg of ice at -9°C C to water at 0°C?
Molodets [167]

Answer:

hence option A is correct

Explanation:

heat required from -9°C to 0°C ice = mass × specific heat of ice ×change in temperature

heat required from -9°C to 0°C ice = 7×2100×9 =132300 J =0.1323 MJ

( HERE SPECIFIC HEAT OF ICE IS A CONSTANT VALUE OF 2100

J/(kg °C )

heat required from  0°C ice to 0°C water = mass× specific heat of fusion of ice

                                                             = 7×3.36×10^5

                                                              = 2.352 × 10^6 J

                                                              = 2.352 MJ

TOTAL HEAT ENERGY REQUIRED = 0.1323 MJ +2.352 MJ

                                                          = 2.4843 MJ

hence option A is correct

5 0
3 years ago
John pushes a box with a constant force as shown in the graph below.
andrew11 [14]
From the graph, it can be seen that the constant force that John exerted in order to move the object is 14N. Work is calculated by multiplying the force with the distance to which the object moves in parallel with the direction of the force. 
                                      Work = Force x displacement
                                      Work = (14 N) x (8 m)
                                        Work = 112 J
The closest value is 110J. Thus, the answer to this item is the second choice. 
4 0
3 years ago
PLSSS HELP I WILL GIVE U BRAINLIEST annabelle and jose are building a complete circuit for their science inquiry in class they w
Agata [3.3K]

Answer:

i think its C hope this is rhight have a good day

Explanation:

6 0
3 years ago
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