Mastering Physics Quiz 1
The muzzle velocity of a bullet fired from a new rifle is 100 m/s. Neglecting air resistance, at the end of one second a bullet fired straight up into the air will have traveled a distance of
(100 - 5) m.
What is the acceleration of a car moving along a straight road that increases its speed from 0 to 100 km/h in 10 s?
10 km/h·s
A projectile is launched vertically at 100 m/s. If air resistance can be ignored, at what speed will it return to its initial level?
100 m/s
While you are in a bus that moves at 100 km/h you walk from the back to the front at 10 km/h. What is your speed relative to the road outside?
110 km/h
What is the instantaneous velocity of a freely falling object 13 s after it is released from a position of rest?
130 m/s
Consider a book that weighs 15 N at rest on a flat table. How many newtons of support force does the table exert on the book?
15 newtons up
A ball player wishes to determine pitching speed by throwing a ball horizontally from an elevation 5 m above ground level. The ball lands 20 m downrange. The player's pitching speed is about
20 m/s
How much support force acts on a 200-N girl standing on a weighing scale?
200N
What is the average speed in kilometers per hour of a horse that gallops a distance of 15 km in a time of 30 min?
30 km/h
A projectile falls beneath the straight-line path it would follow if there were no gravity. How many meters does it fall below this line if it has been traveling for 1 s? For 2 s?
5 m, 20 m
Jason weighs 150 N and sits on his big brother's shoulders. Big brother weighs 400 N. The support force supplied by the floor must be
550 N
What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa?
Galileo found that a heavier stone does not fall significantly faster than a lighter one.
When air resistance is neglected, why does the vertical component of velocity for a projectile change with time, whereas the horizontal component of velocity doesn't change?
Gravity is a purely vertical force.
What did Galileo discover about moving bodies and force in his experiments with inclined planes?
In the absence of a retarding force, a body will keep moving at a constant speed in a straight line forever.
A stone is thrown upward at an angle. What happens to the magnitude of the vertical component of its velocity as it rises? As it falls?
It decreases while rising, but it increases while falling.
When an object is thrown upward, how much speed does it lose each second (ignoring air resistance)?
It loses 10 m/s of speed each second until it reaches the high point, then it gains 10 m/s each second.
A stone is thrown upward at an angle. What happens to the horizontal component of its velocity as it rises? As it falls?
Rising or falling, it does not change.
Which ball (the dropped ball or the ball thrown horizontally) has the greatest speed at the moment of impact?
The ball thrown horizontally
If you push on a crate with a horizontal force of 100 N and it slides at constant velocity, what is the magnitude and direction of the frictional force acting on the crate?
The frictional force on the crate is 100 N opposite the direction of motion.
What is the net force on an object in either static or dynamic equilibrium?
The net force is zero
What is the speed acquired by a freely falling object 5 s after being dropped from a rest position? What is the speed 6 s after?
The speed is 50 m/s after 5 s and 60 m/s after 6 s
A bowling ball at rest is in equilibrium. Is the ball in equilibrium when it moves at constant speed in a straight-line path?
Yes, the bowling ball is in equilibrium because ΣF = 0.
What is the net force on a crate sliding at an unchanging speed when pushed with a steady force of 75 N?
Zero
If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in
a straight-line path.
A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is
about 30 m/s
Galileo discovered that when air resistance can be neglected, all objects fall with the same ______.
acceleration
If Nellie hangs from a horizontal bar that is supported by four vertical ropes, the tension in the ropes
add to equal her weight
What is the gain in speed per second for a freely falling object?
approximately 10 m/s
The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target, when should the crew drop the crate? Ignore air resistance.
before the plane is directly over the target
While an airplane flies at 40 m/s at an altitude of 500 meters, the pilot drops a heavy package that falls to the ground. Neglecting air drag, about where does the package land relative to the plane flying above?
directly below the plane
A pair of wires support a heavy painting. Tension in the wires is greater when they are
not vertical
A hockey puck sliding across the ice finally comes to rest because
of friction
A hunter on level ground fires a bullet at an angle of 10 degrees above the horizontal while simultaneously dropping another bullet from the level of the rifle. Which bullet will hit the ground first?
the dropped bullet
An object is dropped and freely falls to the ground with acceleration g. If it is thrown upward at an angle instead, neglecting air drag, the acceleration along its path will be
the same
A ball rolling down an inclined plane each second picks up ______.
the same amount of speed each second
What is the main difference between speed and velocity?
velocity includes direction, speed does not
A ball is thrown horizontally from a cliff at a speed of 10 m/s . You predict that its speed 1 s later will be slightly greater than 14 m/s . Your friend says it will be 10 m/s. Whos is correct?
you
Nellie pulls with a force of 50 N on a horizontal rope tied to a tree at rest. The net force on the rope is
zero and rope tension is 50 N.
