Physics Ch. 5
a box is dragged without acceleration is a straight-line path across a level surface by a force of 13 N. What is the frictional force between the box and the surface?
13 N
a tow truck exerts a force of 2000 N on a ca, accelerating it at 1 m/s/s. what is the mass of the car?
2000 Kg
when an object reaches terminal velocity it's acceleration is
0 m/s^2
a 10-kg brick and a 1-kg book are dropped in a vacuum. the force of gravity on the 10-kg brick is
10 times as much as the force on the 1-kg book
when a women stands with two feet on a scale, the scale reads 280 N. when she lifts one foot, the scale reads
280 N
you pull horizontally on a 50-kg crate with a force of 450 and the friction force on the crate is 250 N. the acceleration of the crate is
4 m/s^2
a jumbo jet cruises at a constant velocity when the total thrust of the engines on the jet is 50,000 N. how much air resistance acts on the jet?
50,000 N
how does acceleration of an object change in relation to its mass? it is
inversely proportional
if the force acting on a cart doubles what happens to the carts acceleration?
it doubles
suppose a cart is being moved by force. if suddenly a load is dumped into the cart so that the carts mass doubles, what happens to the carts acceleration?
it halves
A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is
its weight
a force of 3 N accelerates a mass of 3-kg at the rate of 1 m/s^2. the acceleration of a mass of 6 kg acted upon by a force of 6 N is
the same
a fluid can be either a liquid or a gas
true
suppose a particle is accelerated through space by a constant 10-N force. suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. the particle
continues at the speed it had when it encountered the second flight.
a heavy person and a light person parachute together and wear the same size parachutes. assuming they open their parachutes at the same time, which person reaches the ground first?
the heavy person
the pascal is a unit of force
false
the speed of an object dropped in air will continue to increase without limit.
false
pressure is defined as
force per area
accelerations are produced by
forces
a 6-N falling object encounters 6 N of air resistance. the magnitude of the net force on the object is?
0 N
a book weighs 4 N. when held at rest in your hands, the net force on the book is
0 N
which of the following would exert the most pressure on the ground?
a women standing in high-heels shoes.
an object has a constant mass. a constant force on the object produces constant
acceleration
the acceleration produced by a net force on an object is
all of the above
you are on a frozen pond, and the ice starts to crack. if you lie down on the ice and begin to crawl, this will
decrease the pressure on the ice.
as a care package falls from high- flying stationary helicopter, it's velocity increases and its acceleration
decreases
when the angle of an incline with a block resting on it increases, the normal support force
decreases
excluding the force due to air pressure, there is only one force acting on a book lying at rest on a tabletop.
false
it is possible for an object in free fall t have zero acceleration
false
a 20-N falling object encounters 4 N of air resistance. the magnitude of the net force on the object is
16 N
A 20-N falling object encounters 4 N of air resistance. The magnitude of the net force on the object is
16n
a girl pulls on a 10-kg wagon with a constant force of 20 N. what is the wagons acceleration?
2 m/s^2
a jet has a mass of 40,000 kg. the trust for each of four engines is 20,000 N. what is the jets acceleration when taking off?
2 m/s^2
suppose the force of friction on a sliding object is 25 N. the force needed to maintain a constant velocity is
25 N
if you pull horizontally on a desk with a force of 150 N and the desk doesn't move, the friction force must be 150 N. now if you pull with 250 N desk slides at constant velocity, the friction force is
250 N
a sports car has a mass of 1500 kg and accelerates at 5 meters per second squared. what is the magnitude of the force acting on the sports car?
7500 N
how much force is needed to accelerate a 4.0-kg physics book to an acceleration of 2.0 m/s^2?
8.0 N
pressure is defined as the force one object exerts on another object
false
the acceleration of an object is inversely proportional to the net force acting on it.
false
a block is at rest on an incline. the force of friction necessary to prevent the block from sliding increases when the incline angle is
increased
the unit of pressure is
newtons per square meter (or pascals)
A tennis ball and a solid steel ball with the same diameter are dropped at the same time. Which ball has the greater force acting on it?
steel ball
the combination of all the forces that act on an object is called the net force
true
the net force on an objecting falling at terminal velocity is zero.
true
a push on a 1-kg brick accelerates the brick. neglecting friction, to equally accelerate a 10-kg brick, one would have to push
with 10 times as much force
