What is the net force on a car if the force of friction is 15 N and the forward force due to the engine is 20 N?

Why does it take longer to boil a kettle of water than to warm the same kettle of water to a lower temperature?

lys-0071 [83]

Answer:

The reason that it takes longer to get the water to boiling temperature than it is to cool it down again is because heating in the most simple sense is inefficient and will cause a lot if energy lost while cooling is to be turn's into quite a efficient process.

Explanation:

6 0

2 years ago

What is the best piece of advice you have ever received or given?

Afina-wow [57]

Answer:Your life is your responsibility.

Explanation:

4 0

3 years ago

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a stone with a mass of 2.40 kg is moving with velocity (6.60î − 2.40ĵ) m/s. find the net work (in j) on the stone if its velocit

ch4aika [34]

By the work energy theorem, the total work done on the stone is given by its change in kinetic energy,

$W = \Delta K = \dfrac m2 ({v_2}^2 - {v_1}^2)$

We have

$\vec v_1 = (6.60\,\vec\imath - 2.40\,\vec\jmath)\dfrac{\rm m}{\rm s} \implies {v_1}^2 = \|\vec v_1\|^2 = 49.32 \dfrac{\rm m^2}{\rm s^2}$

$\vec v_2 = (8.00\,\vec\imath + 4.00\,\vec\jmath) \dfrac{\rm m}{\rm s} \implies {v_2}^2 = \|\vec v_2\|^2 = 80.0\dfrac{\mathrm m^2}{\mathrm s^2}$

Then the total work is

$W = \dfrac{2.40\,\rm kg}2 \left(80.0\dfrac{\rm m^2}{\rm s^2} - 49.32\dfrac{\rm m^2}{\rm s^2}\right) \approx \boxed{36.8\,\rm J}$

5 0

2 years ago

Consider the circuit shown in the figure below. (Let R1 = 3.00 Ω, R2 = 8.00 Ω, and = 10.0 V.). . (a) Find the voltage across R1.

Goryan [66]

You take the inverse of the total resistances of each branch and add them up. So if you have 5ohm, 7 ohm, and 10ohm, you would add 1/5 + 1/7 + 1/10 = 31/70 Then flip it back by either using the x−1 (inverse) key on your calculator or simply dividing 70 by 31 to get a total of 2.26ohms

8 0

3 years ago

Bob is pushing a box across the floor at a constant speed of 1.7 m/s, applying a horizontal force whose magnitude is 70 N. Alice

OlgaM077 [116]

Answer:

a) 70 N, b) b. Each initially applied a force bigger than static friction to get the box moving and accelerating, then when the desired final speed was achieved they reduced the force to make the net force zero.

Explanation:

a) A constant speed means that magnitude of friction force is equal to the magnitude of the external force. The friction force is directly proportional to the normal force, which is equal to the weight of the box. Therefore, the magnitude of the force is 70 N.

b) Alice used initially a greater force to accelerate the box up to needed speed and later reduced the external force to keep speed constant. The right choice is option b.

3 0

3 years ago