Science test, Motion

Neglecting air resistance, when you toss a rock upward, by about how much does its upward speed decrease each second? (a.) 10 m/s (b.) 10 m/s^2 (c.) the answer depends on the initial speed (d.) none of these

(a.) 10 m/s

During each second of free fall, the speed of an object (a.) increase by the same amount (b.) changes by increasing amounts (c.) remains constant (d.) doubles

(a.) increase by the same amount

What is the net force on a box that is being pushed to the left with a force 40 N while it is also being pushed to the right with a force of 50 N? (a.) 10 N to the left (b.) 10 N to the right (c.) 90 N to the left (d.) 90 N to the right

(b.) 10 N to the right

When you stand on 2 bathroom scales, 1 foot on each scale with your weight evenly distributed, each scale will read (a.) your weight (b.) half your weight (c.) zero (d.) actually more than your weight

(b.) half your weight

In 2 secs, a car increases its speed from 30 km/h to 35 km/h while a bicycle goes from rest to 6 km/h. Which has the greater acceleration? (a.) the car (b.) the bike (c.) the accelerations are equal (d.) it is impossible to know from the info provided

(b.) the bike

To be in mechanical equilibrium, an object must be (a.) at rest (b.) moving at constant velocity (c.) either at rest or moving at constant speed (d.) neither at rest nor moving at constant speed

(c.) either at rest or moving at constant speed

According to Galileo, inertia is a (a.) force like any other force (b.) special kind of force (c.) property of all matter (d.) concept opposite to force

(c.) property

If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in (a.) a curved path (b.) an outward spiral path (c.) an inward spiral path (d.) a straight line

(d.) a straight line

A freely falling object has a speed of 40 m/s at 1 instant. Exactly 1 sec later its speed will be (a.) the same (b.) 10 m/s (c.) 45 m/s (d.) greater than 45 m/s

(d.) greater than 45 m/s

If an object moves along a straight-line path at constant speed, then it must be (a.) accelerating (b.) acted on by a force (c.) both of these (d.) neither of these

(d.) neither of these

what is the net force on a box that is being pushed to the left with a force of 50 N while it is also being pushed to the right with a force of 60 N?

10 N right

what is the acceleration of an object in free fall at earth's surface?

10 m/s

how much tension is there in a rope that holds a 20-N bag of apples at rest?

20 N

the scientific unit of Force ( or weight)

Newton

The rate at which velocity changes with time; the change in velocity may be in magnitude, or in direction, or in both. It is usually measured in m/s^2

acceleration

what equation shows the relationship among velocity, time , and acceleration

acceleration change in velocity / time interval

The force of friction acting on an object due to its motion through air

air resistance

why is the support force on an object often called the normal force?

bc it acts at right angles to the surface. but a normal force in another term for right angle

why do we say that velocity is a vector and speed is not a vector?

bc velocity has a direction but speed does not

did Aristotle believe that forces are necessary to keep moving objects moving, or did he believe that, once moving, they would move by themselves?

believed forces are necessary

if we push a crate at constant velocity, how does friction acting on the crate compare with our pushing forces?

constant velocity means no acceleration, no acceleration means net force of zero; friction is equal to magnitude and opposite direction from your pushing force.

when you toss a ball upward, by how much does its upward speed decrease each second?

decrease by 10 m/s each second

a measure of mass per volume for a substance

density

when you weigh yourself, how does the support force of the scale acting on you compare with the gravitational force between you and earth?

equal in magnitude and opposite in direction

the vector sum of forces acting on a non-accelerating object equals zero

equilibrium

a vector quantity that specifies both speed of an object and its direction of motion

equilibrium rule

which dominated Galileo's way of extending knowledge- philosophical discussion or experiment?

experiment

simply states, push or pull

force

what 2 main ideas of Aristotle did Galileo discredit?

forces are needed to keep an object in motion, and heavier objects fall faster

motion under the influence of gravitational pull only

free fall

the resistive force that opposes the motion or attempted motion of an object through a fluid or past another object with which it is in contact

friction

the property of things to resist changes in motion

inertia

what is the name of the property of objects to maintain their states of motion?

inertia

does the speedometer on a vehicle show the average speed or the instantaneous speed?

instantaneous speed

the unit of mass

kg

if you push a heavy crate to the right and it slides, what is the direction of the friction on the crate?

left, it works against whatever direction the object is moving in

1 kg weighs 10 N on earth . would it weigh more or less on the moon?

less

what 2 quantities are necessary to determine a vector quantity?

magnitude and direction

the quantity of matter in an object. more specifically, a measure of the inertia or sluggishness that an object exhibits in response to any effort made to change its state of motion

mass

what were Aristotle's 2 main classifications of motion?

natural and violent motion

the combination of all forces that act on an object

net force

what test tells us whether or not a moving object is in equilibrium?

object is moving in constant speed or it's in rest; if the velocity is not changing

why does the unit of time appear twice in the definition of acceleration?

once for the unit of velocity and again for the interval of time in which the velocity is changing

the equation shows the relationship among speed, distance, and time

s = d/t

the distance traveled per unit of time

speed

the force that supports and object against gravity; often called the normal force

support force

what is the name given to a force that occurs in a rope when both ends are pulled in opposite directions?

tension

how does the direction of a friction force compare with the direction of motion of a sliding object?

the direction of the force of friction is such that it opposes the direction of motion that an object would move if there were no frictional force acting on the object

which has the greater density - 1 kg of water or 10 kg of water

they have the same density

a quantity that specifies as well as magnitude

vector

the force of gravity on an object

weight

which depends on gravity- weight or mass

weight bc all the weight is the amount of gravity pulling down on an object

what are the units of measurement for weight and mass?

weight is newtons mass is kg

what does EF=0 mean?

when the net force on something is 0

suppose you push on a heavy crate, but not hard enough to make it slide. does friction force act on the crate?

yes, the friction force is equal an opposite to the component of the applied force parallel to the surface on which the crate rests

how can you be at rest and also moving at 100,000 km/h at the same time?

you could be at rest but the earth is moving a large amount of speed

where would your weight be greater- on earth or on the moon? where would your mass be greater?

your weight is greater on the earth, but mass is the same bc mass is not a function of gravity