Answer:
Explanation:
Yes she is doing work. With or without the groceries, she is still doing work. She does more work with the groceries than without because Work is defined by F which is defined by mass. The mass increases with the groceries.
The work done is against the force of gravity.
The Earth takes very nearly (365 and 1/4) days to go around the sun.
If our calendar always had 365 days, then the year would end and re-start
too soon, and the beginning of Spring (and every other season) would
eventually drift into the months after March.
If our calendar always had 366 days, then the year would end and re-start
too late, and the beginning of Spring (and every other season) would
eventually drift into the months before March.
We can't make calendars with an extra quarter-day in each year. But we
keep them lined up with the real year by saving up the quarters, and adding
one full day to the calendar every 4 years.
The gravitational force of the planet pulling on the sun is equal to the gravitational force of the sun pulling on the planet
Explanation:
We can solve this problem by applying Newton's third law, which states that:
<em>"When an object A exerts a force (called </em><em>action</em><em>) on an object B, then object B exerts an equal and opposite force (called </em><em>reaction</em><em>) on object A"</em>
In this problem, we can identify:
- The sun as object A
- The planet as object B
By applying Newton's third law, we can state that:
- The action is the gravitational force exerted by the sun on the planet
- The reaction is the gravitational force exerted by the planet on the sun
According to the law, the two forces are equal in magnitude and opposite in direction: so, we can conclude that
The gravitational force of the planet pulling on the sun is equal to the gravitational force of the sun pulling on the planet
Learn more about Newton's third law:
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Answer:
After 15 seconds, the green car will catch up with the blue car
Explanation:
Let the time for the green car to catch up with the blue car be T
When the green car catches up to the blue car, the distances covered by each car after time T will be equal. Also, their velocities at that instant will be equal
Distance covered by blue car after time T is given by: s = ut + 0.5 at²
Where u = 0, a = 0.2 m/s², t = T
S = 0.5 × 0.2 × T² = 0.1 T²
Velocity of blue car, v = u+ at
v = 0.2T
Distance covered by green car at T is given as: S = Velocity × time
Where v = 0.2T, t = T - 7.5 (since the blue car started 7.5 seconds earlier)
S = 0.2T (T - 7.5)
S = 0.2 T² - 1.5T
Equating the distance covered by the two cars
0.2T² - 1.5T = 0.1T²
0.1T² - 1.5T = 0
T(0.1T - 1.5) = 0
T = 0 or
T = 1.5/0.1 = 15 secs
Therefore, after 15 seconds, the green car will catch up with the blue car