Physics HW 2
A 10-N falling object encounters 10 N of air resistance. The net force on it is
0 N.
A hockey puck slides across a frozen pond. If ice friction and air resistance are neglected, the force needed to keep the puck sliding at constant velocity is
0 N.
A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration is
0 m/s^2
When a baseball player hits a ball with a force of 1000 N, the ball exerts force on the bat of
1000 N
Arnold Strongman and Suzie Small have a tug-of-war on a polished floor. Arnold wears socks and Suzie wears gym shoes. The likely winner is
Suzie
Consider two planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them is also doubled, then the force between them is
Twice as much
If the mass of an object does not change, a constant net force on the object produces constant
acceleration
Newton's second law directly involves
acceleration
A friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair, no wall, no tricks. You
agree that it can't be done
An archer shoots an arrow. If the action force is the bowstring on the arrow, the reaction is the
arrow's push on the bowstring
A given net force propels an object along a straight-line path. If the net force were doubled, its acceleration would
be half
A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration
decreases
When an object falls through the air, as velocity increases its acceleration
decreases
When you toss a coin straight up, it moves upward, turns around, and drops. During this time the acceleration of the coin is
downward and constant
Two objects of the same size, but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
heavier object.
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
increases
A projectile is fired horizontally. With no air resistance it maintains its horizontal component of velocity because
no horizontal forces act on it
Roll a bowling ball off the edge of a table. As it falls, its horizontal component of motion
remains constant
The air resistance of falling is greatly affected by an object's frontal area
speed
Newton discovered
that gravity is universal
A hunter aims a rifle at an angle of 10° above the horizontal. The hunter fires a bullet while simultaneously dropping another bullet from the side of the rifle. Which bullet hits the ground first?
the dropped one
A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first?
the light woman
The attraction of a person's body toward Earth is called weight. The reaction to this force is
the person's body pulling on Earth
The fastest moving planet in a solar system is
the planet nearest the sun
A ball is thrown upwards and caught when it returns. Neglecting air resistance, the speed with which it is caught is
the same as its initial speed
A 10-kg brick and a 1-kg book are dropped in a vacuum. The acceleration of the 10-kg brick is
the same as that of the 1-kg book
A "weightless" astronaut in an orbiting space vehicle is
without a support force
An object in motion tends to remain in motion
without the need of a force
When a falling object has reached its terminal velocity, its acceleration is
zero
