EPS Unit One Test
It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?
10 N
What is the equation for free fall speed?
10t
It takes 6 s for a stone to fall to the bottom of a mine shaft. How deep is the shaft?
180 meters
Exert 100 J in 50 s and your power output is
2 W
The 2-ton Goodyear blimp floats in the air. The buoyant force acting on it is
2 ton
If a freely falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s/s, then its speed reading would increase each second by
20 m/s
What would be the buoyant force on a 20 ton ship floating in the ocean?
20 tons
How much power is extended when lifting a 1000-N load a vertical distance of 4 m in a time of 2 seconds? How about 1 second?
2000 W (1000 x 4/2); 4000 W
A car traveling at 22 m/s comes to an abrupt halt in 0.1 s when it hits a tree. What is the deceleration in meters per second per second of the car?
220 m/s (22/0.1)
A 2000-kg car experiences a braking force of 10,000 N and skids to a stop in 6 s. The speed of the car just before the brakes were applied was
30 m/s
One-half second after starting from rest, a freely falling object will have a speed of about
5 m/s
What is work measured in?
Joules (J)
The planet Jupiter is about 300 times as massive as the earth, yet on its surface you would weigh only about 3 times as much. This is because
Jupiter's radius is 10 times the earth's radius.
Kinetic energy equation
KE=1/2mv^2
An object is placed exactly halfway between the earth and the Moon. The object will fall toward the
Earth
Gravitational force equation
F = G x m1m2/r^2
equation for work
Force (N) x distance (m)
If the smallest orbit velocity around Earth is about 8 km/s. The smallest orbit velocity around the Moon would be
Less than 8 km/s
How far must one travel to get away from the earth's gravitational field?
NEVER!
What did Aristotle believe about motion?
Natural motion and violent motion (heavy objects fall faster than lighter ones)
How does the mass of an object vary with location?
Not at all! Only weight varies with location, not mass.
Some satellites are always at the same position in the sky. This is due to the fact that these satellites are
Orbiting Earth with a 24-hour period
Equation for power
P=W/t (work/time)
potential energy equation
PE=mg x height
What did Galileo believe about motion?
Proved Aristotle wrong by Tower of Piza. Also said that if friction was absent a force isn't needed to keep an object moving.
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
A rifle is aimed at an angle of 10° above the horizontal. A bullet is fired while at the same time another bullet is dropped from the level of the rifle. Which bullet will hit the ground first?
The dropped one
What component is used for hangtime? What is the longest possible hangtime?
The vertical distance; 1 second
A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle to undergo the greatest change in velocity will be the
Volkswagon (less mass)
Does a 2 kg iron block have twice as much inertia, mass, weight, and volume as a 1 kg bunch of bananas?
Yes to all but volume
If the Sun were twice as massive, a) both of these b) its pull on the earth would double. c) neither of these d) the pull of the earth on the Sun would double.
a) both of these
Tidal forces, due to the differences in gravitational pulls across a body, get weaker as the distance is a) cubed. b) neither of these c) squared.
a) cubed
The force of gravity acts on all apples on an apple tree. Some apples are twice as far from the ground as others. These twice-as-high apples, for the same mass, have a) practically the same weight. b) 1/2 the weight. c) 1/4 the weight.
a) practically the same weight.
When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, the time of the impact is about 10 times more than for a stiff-legged landing. In this way the average force your body experiences is reduced by
about 10 times
Hang from a pair of gym rings and the upward support forces of the rings will always
add up and equal to your weight
Which has zero acceleration? An object A) at rest. B) moving at constant velocity. C) in mechanical equilibrium. D) all of these E) none of these
all of these
When you float in a pool, the buoyant force acting on you is equal to your weight. When you float higher in The Great Salt Lake in Utah, the buoyant force that acts on you is
also equal to your weight.
Equation for momentum
p=mv
As an object get deeper in water _______ increases and _______ stays the same
pressure; bouyant force
The period of a planet, which is the time it takes for a complete revolution, depends on the planet's
radial distance
A heavy rock and a light rock in free fall have the same acceleration. The reason the heavy rock doesn't have a greater acceleration is that the
ratio of force to mass is the same (more mass = more inertia)
A tennis ball is thrown out and up at 50° with the horizontal. While traveling, its horizontal velocity
remains the same
What is inertia?
resistance to change in motion (all objects with mas have it; more mass = more inertia)
The reason the Moon does not crash into Earth is that
the Moon has a sufficient tangential speed.
After a snowball thrown completely upward reaches the top of its path and begins to fall back down, its acceleration is (neglect air resistance)
the same as at the top
Galileo's interpretation of motion differed from Aristotle's in that Galileo emphasized
time rates
Tidal forces in general are the result of
unequal forces acting on different parts of a body.
The density of a submarine underwater is about the same as the density of
water
Dams built in rivers and other bodies of water will be thinner at the top than at the bottom because
water pressure is greater with increasing depth.
The earth is closer to the Sun in January than in July, which accounts for the fact that the highest high tides in the northern hemisphere occur in
winter
What is the constant for g?
10
Starting from rest, the distance a freely falling object will fall in 0.5 s is about
1.25 m
What is the equation for the distance of upwardly launched projectiles?
1/2(10)t^2 (5t^2)
What is the equation for free fall distance?
1/210t squared
A woman lifts a box from the floor. She then moves with constant speed to the other side of the room, where she puts the box down. How much work does she do on the box while walking across the floor at constant speed?
0 J
A 10-N falling object encounters 10 N of air resistance. The net force on the object is
0 N
The hang time of a player who moves horizontally 2.0 m during a 1.25-m-high jump is
1 s
A 2-kg mass is held 4 m above the ground. What is the approximate potential energy of the mass with respect to the ground?
80 J
One kilograms weighs ____ Newtons
9.8
A heavy object and a light object are dropped at the same time from rest in a vacuum. The heavier object reaches the ground
at the same time as the lighter object.
The International Space Station orbits at distances greater than 150 km above the surface in order to be above Earth's
atmosphere
A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill, the heavy truck will have greater a) speed b) momentum c) accelaration d) all of these e) none of these
b) momentum
When a person is partly or completely immersed in water, they are buoyed up
by a force equal to the weight of liquid displaced.
It takes Neptune a longer time to orbit the Sun than earth because it a) has farther to travel. b) is slower. c) both of these d) none of these
c) both of these
Bouyant force is greater on a a) 1 cubic centimeter block of lead. b) 1 cubic centimeter block of foam. c) is the same on each.
c) is the same on each
Buoyant force is greatest on a submerged a) 1-kg block of styrofoam. b) 1-kg block of lead c) is the same on each
c) is the same on each
While a car travels around a circular track at constant speed, its a) Acceleration is zero b) velocity is zero c) none of these
c) none of these
A nerf dart is fired vertically from Earth at 10 km/s. The dart will a) go into an elliptical orbit about Earth. b) go into circular orbit about Earth c) rise and fall back to Earth's surface. d) none of these
c) rise and fall back to Earth's surface
What is the equation for acceleration?
change in velocity/time interval
If Earth's mass decreased to one-half its original mass with no change in radius, then your weight would
decrease to one-half your original weight.
A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
directed downward
A floating object....
displaces a weight of fluid equal to its own weight
In bungee jumping, the change in a jumper's kinetic energy equals the average force of the bungee cord multiplied by the stretching
distance (change in kinetic energy = work)
When a weather balloon rises higher into the atmosphere, its a) mass decreases. b) density increases. c) volume decreases. d) weight increases. e) none of these
e) none of these
Whereas Aristotle relied on logic in explaining nature, Galileo relied on
experiment
Acceleration equation
final velocity-initial velocity/time
A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is
greater
A bullet is fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun a) because momentum is conserved. b) if the mass of the bullet equals the mass of the gun. c) because velocity is conserved. d) because both velocity and momentum are conserved. e) none of these
if the mass of the bullet equals the mass of the gun
If the mass of an object is doubled, the weight...
is also doubled
Two pool balls, each moving at 2 m/s, roll toward each other and collide. Suppose after bouncing apart, each moves at 4 m/s. This collision violates conservation of a) momentum b) kinetic energy c) both of these d) none of these
kinetic energy
A ball thrown straight upward takes 10 s to go up and return to the ground. Because of air resistance, the time taken for the ball just to go up is a) less than 5 s b) 5 s c) greater than 5 s
less than 5 s
Pumice is a volcanic rock that floats. Its density is
less than the density of water
What is the difference between mass and weight?
mass is the amount of matter in an object, weight is the measure of the pull of gravity on an object
Strange as it may seem, it is just as hard to accelerate a car on the Moon as it is to accelerate the same car on Earth. This is because the
mass of the car is independent of gravity. (a = f/m)
When the net force of something is zero,
mechanical equilibrium