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Question
A common 5-liter metal can will float in air if it isA) evacuated of air.
B) filled with a very large amount of helium.
C) thrown high enough.
D) no way, unless the displaced air weighs more than the can and its contents!
Answer
This answer is hidden. It contains 1 characters.
Related questions
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If the speed of a bicycle is reduced to half before skidding to a stop, it will skid
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B) one-fourth as far.
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D) none of the above
Q:
A cannonball has more kinetic energy than the recoiling cannon from which it is fired because the force on the ball
A) is more concentrated.
B) meets less resistance than the cannon on the ground.
C) acts over a longer distance.
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If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be
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Q:
When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is
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Q:
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C) decreased impulse.
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Q:
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A) momentum.
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B) 2,000 kg m/s.
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B) 12 kg.
C) 16 kg.
D) 144 kg.
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Q:
The speed of a 4-kg ball with a momentum of 12 kg m/s is
A) 3 m/s.
B) 4 m/s.
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D) 48 m/s.
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Q:
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A) zero.
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Q:
A river 100 m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water leaves the west bank. To land at a point due east of its starting point, the boat must be pointed
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Q:
As the sloped surface supporting a shoe becomes steeper
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B) the normal force becomes less.
C) friction needed to keep it at rest increases.
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A) remains equal to mg at all angles.
B) decreases as the slope of the ramp increases.
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Q:
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A) less than half her weight.
B) half her weight.
C) more than half her weight.
D) her weight.
Q:
When a cannonball is fired from a cannon, which undergoes the greater acceleration?
A) the cannonball
B) the recoiling cannon
C) both the same
Q:
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A) heavier car.
B) lighter car.
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Q:
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A) somewhat greater than Moon's pull on Earth.
B) the only force acting between Earth and Moon.
C) equal in magnitude to the force that Moon pulls on Earth.
Q:
As a ball falls, the action force is the Earth's pull on the ball. The reaction force is the
A) air resistance acting against the ball.
B) acceleration of the ball.
C) ball's pull on Earth.
D) none of the above
Q:
To produce an acceleration to a system there
A) must be a net force on the system.
B) may or may not be a net force on the system.
C) must be acceleration outside the system also.
Q:
An archer shoots an arrow. Consider the action force to be the bowstring against the arrow. The reaction to this force is the
A) combined weight of the arrow and bowstring.
B) friction of the ground against the archer's feet.
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Q:
A fast-moving missile soaring overhead possesses
A) speed.
B) force.
C) both of these
D) neither of these