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Irina-Kira [14]
3 years ago
11

What is a property of “normal force”? a. It always points perpendicular to the contact surface. b. It always points parallel to

the contact surface. c. It always points up. d. It always completely counters gravity.
Physics
1 answer:
OleMash [197]3 years ago
6 0

Answer:

a. It always points perpendicular to the contact surface.

Explanation:

"Normal" means perpendicular.  Normal forces are always perpendicular to the contact surface.

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A system gains 757 kJ757 kJ of heat, resulting in a change in internal energy of the system equal to +176 kJ.+176 kJ. How much w
Alecsey [184]

Answer:

581 kJ, work was done by the system

Explanation:

According to the first law of thermodynamics:

\Delta U = Q-W

where

\Delta U is the change in internal energy of the system

Q is the heat absorbed by the system (positive if absorbed, negative if released)

W is the work done by the system (positive if done by the system, negative if done by the surrounding)

In this problem,

Q=+757 kJ

\Delta U = +176 kJ

Therefore the work done by the system is

W=Q-\Delta U=757 kJ-176 kJ=+581 kJ

And the positive sign means the work is done BY the system.

5 0
3 years ago
The two blocks in oscillate on a frictionless surface with a period of 1.5 s. The upper block just begins to slip when the ampli
Setler79 [48]

Answer:

0.72

Explanation:

T = Time period of oscillation = 1.5 s

Angular frequency is given as

w = \frac{2\pi }{T}\\w = \frac{2(3.14) }{1.5}\\w = 4.2 rad/s

A = Amplitude of oscillation = 40 cm = 0.40 m

\mu = Coefficient of static friction = ?

a = acceleration of the block

m = mass of the block

Maximum acceleration of the block is given as

a = Aw^{2}

frictional force is given as

f = \mu mg

As per newton's second law

f = ma \\\\\mu mg = ma \\\mu g = a\\\mu g = Aw^{2}\\\mu (9.8) = (0.40)(4.2)^{2}\\\mu = 0.72

8 0
3 years ago
Squids propel themselves by expelling water. They do this by keeping water in a cavity and then suddenly contracting the cavity
Musya8 [376]

Answer:

v_squid = - 2,286 m / s

Explanation:

This exercise can be solved using conservation of the moment, the system is made up of the squid plus the water inside, therefore the force to expel the water is an internal force and the moment is conserved.

Initial moment. Before expelling the water

          p₀ = 0

the squid is at rest

Final moment. After expelling the water

         p_{f} = M V_squid + m v_water

         p₀ = p_{f}

          0 = M V_squid + m v_water

           c_squid = -m v_water / M

The mass of the squid without water is

            M = 9 -2 = 7 kg

let's calculate

           v_squid = 2 8/7

           v_squid = - 2,286 m / s

The negative sign indicates that the squid is moving in the opposite direction of the water

8 0
3 years ago
Plants cause weathering, too. a seed that falls into a crack in a rock may grow there. growing roots may push on and enlarge the
Helga [31]

The process which involves plants to cause weathering to a seed that falls into a crack in a rock therefore, breaking apart the rock is called Mechanical weathering.

<h3>Mechanical weathering</h3>

This is defined as the set of weathering processes that break apart rocks into particles (sediment) through physical processes. The most common form of mechanical weathering is the freeze-thaw cycle. Water seeps into holes and cracks in rocks then the water freezes and expands, therefore making the holes larger eventually making the rock split apart.

Read more on Mechanical weathering:

brainly.com/question/857495

3 0
2 years ago
A satellite was in two separate crashes. In both crashes, the satellite had the same mass. Engineers want to know about the spee
Komok [63]

Answer:

The fastest satellite must change orbit

The most massive body (m₁) transfers more momentum to the satellite,

Explanation:

For this problem we consider a system formed by the satellite and each of the bodies with which it collides, in this system the forces during the collision are internal, the amount of movement must be conserved. Let's write the momentum is two instants

Most massive body (m1)

initial. Before the crash

      p₀₁ = M v + m₁ v₁

after the crash

      p_{f1} = M v´ + m₁ v₁´

how momentum is conserved

     p₀ = p_{f}

Lighter body (m2)

      p₀₂ = M v + m₂ v₂

       p_{f2} = M v´ + m₂ v₂´

           

Let's clarify that the speed of the satellite and the object do not have the same direction, in general these shocks are elastic.

We can see that  p₀₁> p₀₂

Let us analyze the two cases when the body collides, The most massive body (m₁) transfers more momentum to the satellite, therefore there must be a greater change in its momentum and velocity.

The fastest satellite must change orbit, thus rotating at a different distance from Earth

5 0
3 years ago
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