Explain why sound is more clear at night than the day

I just don't know how to do the question (a) and (b)

ozzi

Using the equation

$F=ma$

we can observe that you have to apply a non-zero net force to an object in order to make it accelerate. In fact, if the net force is zero you have

$0=ma \iff a=0$

Since we're assuming $n\neq 0$

Now, if the 12N force is applied, the object moves with a constant speed. A constant speed means no acceleration, since by definition the acceleration is a change in speed.

If this sounds counterintuitive to you (why I'm applying a force but I have to acceleration?) think of when we drive a car: even if you want to keep your speed constant, you still have to use the gas pedal, just enough so that the push of the motor balances exactly the road/wheels friction. If you give less gas, the friction becomes stronger, and the car slows down. If you give more gas, the motor push becomes stronger, and the car accelerates.

Back to your exercise: constant speed means to acceleration, so the net force must be zero. This implies that the friction force is exactly 12N.

If the force is increased to 18N, there will be a net force of 6N pushing the object, causing it to accelerate. Using again the same equation of before, and plugging the 3kg mass in the equation, we have

$F=ma \iff 6=3a \iff a=2$

So, the object moves with constant acceleration and initial speed of 10m/s for 0.2 seconds. It's final speed will be

$v = v_0+at = 10+2\cdot 0.2 = 10.4$

5 0

3 years ago

Predict whether an element with a valence of 8 is mostly likely form ionic bonds ,covalent bonds or no chemical bonds with other

spin [16.1K]

An element with a valence of 8 are most likely noble gases (He, Ne, Ar, etc) which means they're already stable so they dont need to undergo chemical bonds with another atom because they already have a full valence shell.

4 0

3 years ago

Read 2 more answers

Two students walk in the same direction along a straight path at a constant speed. One walks at a speed of 0.90 m/s and the othe

mr Goodwill [35]

Answer:

A. 456 seconds

Explanation:

We are given that two students walk in the same direction along a straight path at a constant speed.

One student walks with a speed=0.90 m/s

second student walks with speed=1.9 m/s

Total distance covered by each students=780 meter