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3 years ago

Which would show an example of how physical changes are reversible?

Physics

2 answers:

kondor19780726 [428]3 years ago

8 0

Answer:

Melting tin and then cooling it into a mold

Explanation:

When you melt something, and when it cools it returns to its physical state, therefore the physical changes are reversible. For example, take chocolate. When chocolate melts its liquid, then when it's in a colder situation it becomes solid again and so on, the changes are reversible.

il63 [147K]3 years ago

8 0

Answer:

Explanation:

the physical change was the gold bar being cut and if it is put back together the physical change is reversed

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A 15 N force and a 45 N force act on in object in opposite directions. What is the net force on the object?

vovikov84 [41]

Answer:

30N in the direction the 45N acts.

Explanation:

Fnet = F1 + F2 (the vector sum of the forces)

Assigning a positive direction to the 45N force and a negative direction to the 15N force gives:

Fnet = 45 - 15

Fnet = 30N

Since the answer is positive, it is in the direction the 45N force acts.

7 0

3 years ago

Understand that the acceleration vector is in the direction of the change of the velocity vector. In one dimensional (straight l

MaRussiya [10]

Answer:

a = √ (a_t² + a_c²)

a_t = dv / dt , a_c = v² / r

Explanation:

In a two-dimensional movement, the acceleration can have two components, one in each axis of the movement, so the acceleration can be written as the components of the acceleration in each axis.

a = aₓ i ^ + a_y j ^

Another very common way of expressing acceleration is by creating a reference system with a parallel axis and a perpendicular axis. The axis called parallel is in the radial direction and the perpendicular axis is perpendicular to the movement, therefore the acceleration remains

a = √ (a_t² + a_c²)

where the tangential acceleration is

a_t = dv / dt

the centripetal acceleration is

a_c = v² / r

8 0

3 years ago

2 kilogram bowling ball sits on top of a building that is 40 m the object has k e or g p e or both be sure to include the correc

Licemer1 [7]

GPE=mass*GFS*height
2kg*9.8N/Kg*40m -I've used the Grabitational field strength of the earth's
surface

=784J

7 0

3 years ago

Scientists plan to release a space probe that will enter the atmosphere of a gaseous planet. The temperature of the gaseous plan

lianna [129]

Answer: E. 450 K

Explanation:

It is given that the temperature of the gaseous planet is linearly related with height of the atmosphere. we can write this in the mathematical equation:

y = m x +c

where y is the temperature values, x is height, m is the slope and c is the y-intercept. we have been given two sets of value in the image, using which we can find the value of slope in y-intercept.

at x = 18.40 km, y = 147.54 K

⇒147.54 = 18.40 m + c

⇒c = 147.54 - 18.40 m ..(1)

at x =78.11 km, y = 567.00 K

⇒567.00 =78.11 m + c ..(2)

Put equation 1 in 2 and solve:

⇒567.00 =78.11 m + 147.54 - 18.40 m

⇒419.46 = 59.71 m

⇒ m =419.46 ÷59.71 = 7.025 K/km

c = 147.54 - 18.40 × 7.025 = 18.28 K

At height, x = 61.5 km the approximate temperature is :

y = 7.025 K/km × 61.5 km + 18.28 K = 450.3 K