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Blababa [14]
3 years ago
7

If the actual frictional force is equal to 1 lb., then how much effort (force) would be required to drag a 90 lb. box up the pla

ne?
A. 10+ lb.
B. 10- lb.
C.9+ lb.
D. 9- lb.

Could you also explain this? I am having a hard time understanding.

Physics
1 answer:
Alborosie3 years ago
3 0
Resolving 90 lb along the incline;

The resultant weight along the incline = 90 Sin ∅ = 90*H/90H = 90*1/9 = 9 lb.

The effort must overcome the resultant weight along the incline as well as the frictional force.
That is,
Fe > 9+1
Fe > 10 lb

Therefore,
Fe = 10+ lb

And the correct answer is A.
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Gravitational force depends on the mass of an object.
vampirchik [111]

Answer:

sun, earth, capitol building, human, atom

Explanation:

Gravity is directly proportional to the size of an object. Therefore, the object with the most mass will have the greatest force of gravity. We know this from the equation. F = G\frac{m_1m_2}{r^2}

4 0
3 years ago
What happens to molecules when their kinetic energy decreases?
Illusion [34]

Answer:

The speed of molecule decreases and temperature also decreases

Explanation:

Kinetic energy of the molecules of a subsance is directly proportional to the temperature of molecule So as the kinetic energy decrease, temperature also decreases. decreses their speed.

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3 years ago
What type of glass absorbs light and does not allow light to pass through it?
sesenic [268]

opaque glass does not allow light to pass through it.

8 0
3 years ago
Identify the conditions for an elastic collision in a closed system. Check all that apply.
s344n2d4d5 [400]

Answer:

In an elastic collision:

  • There is no external net force acting. Thus, Momentum before and after collision is equal. Momentum remains conserved.
  • Total energy always remains conserved as energy cannot be created nor destroyed. It can change from one form to another.
  • There is no lost due to friction in elastic collision. So the kinetic energy is also conserved.
  • Velocities may change after collision. If the masses are equal, the velocities interchange.

When one object is stationary:

Final velocity of object 1:

v₁ = (m₁ - m₂)u₁/(m₁ +m₂)

Final velocity of object 2:

v₂ = (2 m₁ u₁)/(m₁+m₂) =

  • Objects do not stick together in elastic collision. They stick together in inelastic collision.
  • One object may be stationary before the elastic collision.

Thus, conditions for an elastic collision:

  • Energy is conserved.
  • Velocities may change.
  • Momentum is conserved.
  • Kinetic energy is conserved.
  • One object may be stationary before the elastic collision.
7 0
3 years ago
Read 2 more answers
A person fires a 38 gram bullet straight up into the air. It rises, then falls straight back down, striking the ground with a sp
Y_Kistochka [10]

Answer:

Force exerted = 25.41 kN

Explanation:

We have equation of motion

      v² = u²+2as

u = 345 m/s, s = 8.9 cm = 0.089 m, v = 0 m/s

     0² = 345²+2 x a x 0.089

       a = -668679.78 m/s²

Force exerted = Mass x Acceleration

Mass of bullet = 38 g = 0.038 kg

Acceleration = 668679.78 m/s²

Force exerted = 25409.83 N = 25.41 kN

4 0
4 years ago
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