An object that is in free fall seems to be (D) weightless.
Objects which are in free fall are said to be weightless because they only have the force of gravity acting upon them. Objects in free fall do not experience air resistance.
Answer:
efficiency of a machine is less than 100% because some part is energy is utilized to overcome some opposing forces like friction which is wasted as heat ,sound energy etc
Explanation:
For any periodic wave
<span>v = f λ </span>
<span>where </span>
<span>v = velocity </span>
<span>f = frequency </span>
<span>λ = wavelength (distance between 2 successive crests) </span>
<span>This means that </span>
<span>λ = v/f </span>
<span>Assuming that v stays the same while f increases, λ must DECREASE.
I hope this helps
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Answer:
d. the voltage difference between the ends of each resistor is the same.
Explanation:
A resistor is a circuit component that offers opposition to the flow of current. Resistors may be connected in series or in parallel.
Resistors in parallel are connected at common junctions. The potential difference (voltage difference between the ends of each resistor) is the same for each resistor in a parallel connection while the current across each resistor is different.
Answer:
72,300 years.
Explanation:
- Initial mass of this sample: 504 grams;
- Current mass of this sample: 63 grams.
What's the ratio between the current and the initial mass of this sample? In other words, what fraction of the initial sample hasn't yet decayed?
.
The value of this fraction starts at 1 decreases to 1/2 of its initial value after every half-life. How many times shall 1/2 be multiplied to 1 before reaching 1/8? 
. It takes three half-lives or 
years to reach that value.
In certain questions the denominator of the fraction is large. It might not even be an integer power of 2. The base-x logarithm function on calculators could help. Evaluate
to find the number of half-lives required. In case the base-x logarithm function isn't available, but the natural logarithm function 
is, apply the following expression (derived from the base-changing formula) to get the same result:
.
