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mixas84 [53]
3 years ago
8

a car traveling at 24 m/s starts to decelerate steadily. It comes to a complete stop in 6 seconds what is its acceleration?

Physics
1 answer:
Irina18 [472]3 years ago
8 0
We can solve for the acceleration by using a kinematic equation. First we should identify what we know so we can choose the  correct equation.

We are given an original velocity of 24 m/s, a final velocity of 0 m/s, and a time  of 6 s. We and looking for acceleration (a) in m/s^2.

The following equation has everything we need:

v_f=v_i + at

So plug in the known values and solve for a:

0 = 24 + 6a

-24 = 6a

a = -4 m/s^2
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E) Thermal energy is released during
vichka [17]

Answer:

e) True, f) False

Explanation:

e) Let consider a close system, that is, a system with no mass interactions with surroundings. Then, we get the following expression by the First Law of Thermodynamics:

Q_{net,in} - W_{net, out} = \Delta U (1)

Where:

Q_{net, in} - Net input heat, measured in joules.

W_{net, out} - Net output work, measured in joules.

\Delta U - Change in thermal energy, measured in joules.

Please notice that work comprises all kind of work (i.e. mechanical, electric, magnetic), whereas heat comprises all heat interactions including chemical and radioactive phenomena.

If thermal energy is released, then \Delta U < 0, which is caused by three scenarios:

(i) Q_{net,in} < 0, W_{net, out} < 0, |Q_{net,in}|>|W_{net,out}|

(ii) Q_{net, in} > 0, W_{net,out} > 0, |Q_{net,in}|

(iii) Q_{net,in}< 0, W_{net, out}>0

In the case Q_{net,in} > 0, W_{net, out}, the thermal energy of the system is increased. Therefore, thermal energy is released during some energy conversions. Answer: True

f) A liquid solidifies when temperature goes below point of fusion, meaning a realease of heat with no work interactions. That is:

Q_{net, in} = \Delta U, Q_{net, in} < 0 (2)

If Q_{net, in} < 0, then  \Delta U < 0. Then, if a liquid absorbs heat energy, then thermal energy is increase and the liquid does not solidifies. Answer: False.

7 0
2 years ago
An object that is 3 times higher than another object of the same mass will
uranmaximum [27]

Answer: I feel that 3 is the answer

Explanation: Let there be 2 objects, A and B

A is at height of 5m whereas B is at height of 15m

so over here let the gravitational potential energy of A be x

and since B is 3 times higher than A B=3x

Since, earth is considered to be the point where gravitational potenial is 0

So hence forth and object 3 times up will have 3 times the gravitational potential energy of A

3 0
3 years ago
A physics student drops a rock from a 55m cliff. How long does it take to hit the ground?
lara [203]

Answer: 9.9 seconds

Explanation:

that's just how long it takes

6 0
3 years ago
Read 2 more answers
BRAINLEST FOR CORRECT ANSWER PLEASE
Nata [24]

Answer:

Sledgehammer A has more momentum

Explanation:

Given:

Mass of Sledgehammer A = 3 Kg

Swing speed = 1.5 m/s

Mass of Sledgehammer B = 4 Kg

Swing speed = 0.9 m/s

Find:

More momentum

Computation:

Momentum = mv

Momentum sledgehammer A = 3 x 1.5

Momentum sledgehammer A = 4.5 kg⋅m/s

Momentum sledgehammer B = 4 x 0.9

Momentum sledgehammer B = 3.6 kg⋅m/s

Sledgehammer A has more momentum

5 0
2 years ago
Find the energy in Joules required to lift a 55.0 Megagram object a distance of 500 cm.
fredd [130]

Energy to lift something =

               (mass of the object) x (gravity) x (height of the lift).

BUT ...

This simple formula only works if you use the right units.

Mass . . . kilograms
Gravity . . . meters/second²
Height . . . meters

For this question . . .

Mass = 55 megagram = 5.5 x 10⁷ grams = 5.5 x 10⁴ kilograms

Gravity (on Earth) = 9.8 m/second²

Height = 500 cm  =  5.0 meters

So we have ...

Energy = (5.5 x 10⁴ kilogram) x (9.8 m/s²) x (5 m)

            =  2,696,925 joules .

That's quite a large amount of energy ... equivalent to
straining at the rate of 1 horsepower for almost exactly an
hour, or burning a 100 watt light bulb for about 7-1/2 hours.

The reason is the large mass that's being lifted.
On Earth, that much mass weighs about 61 tons.

7 0
2 years ago
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