Question

What are some tricky acceleration questions

Answer 1

1).  A mass of 75 kilograms has an acceleration of 9.8 meters per second²
      when it's dropped near the Earth's surface. 

     a).  Does the same 75 kilogram mass have bigger or
           smaller acceleration when it's dropped on the Moon ?
    
     b).  What it its acceleration on the moon ?

     c).  What would the mass have to be in order to have the same
           acceleration on the moon that the 75kg has on Earth ?
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2).  In 1735 off the south coast of Jamaica, southwest of Kingston, near
where Jamaica's Norman Manley International Airport is today, a British
ship of His Majesty's Navy fired a cannonball at one of the many pirate
ships that used to sail there.

The pirate ship was three miles away, but the British Navy ship had a
very powerful cannon.  So it was able to fire the cannonball in a low arc
that never got too high up.  In fact, the shot never got more than 200 feet
above the sea, but it still reached all the way to the pirate ship, scored a
direct hit amidships her starboard beam, and sent her straight to the bottom,
leaving nothing but a spinning pit of salty bubbles to show where she had sunk.
Arrgghhh ! 

The arc of the cannonball was 200 feet high and three miles long.
Where did it have the greatest acceleration ? 
Where did it have the smallest acceleration ? 
(Ignore air resistance.  Pretend there was no air.)
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3).  Which objects have accelerated motion, and
      which objects have un-accelerated motion ?

     a). a car driving along a straight road at 30 mph

     b). a car driving along a straight road at 30 mph
          with the driver's foot on the gas pedal

     c). a car driving along a straight road at 30 mph
          with the driver's foot on the brake pedal

     d). a car driving around a curve in the road at 30 mph

     e). a spacecraft on its way to the moon, moving away
          from Earth at 5,000 miles per hour

     f). a TV satellite, weather satellite, or GPS satellite, traveling at a
         constant speed in a perfectly circular orbit around the Earth

     g). a spacecraft on its way to the moon, about 10,000 miles
          from the moon and falling towards it

Answer 2

Problem # 1

Do heavier objects fall more slowly than lighter objects?

Answer
No. If an object is heavier the force of gravity is greater, but since it has greater mass the acceleration is the same, so it moves at the same speed (if we neglect air resistance). If we look at Newton's second law, F = ma. The force of gravity is F = mg, where m is the mass of the object and g is the acceleration due to gravity.

Equating, we have mg = ma. Therefore, a = g.


If there was no air resistance, a feather would fall at the same speed as an apple