Physics Exam 2

two people pull on a rope in tug-of-war. each pull with 400N of force. what is the tension in the rope?

0

suppose a high flying jet cruises with a constant velocity when the thrust from its engines is a constant 80,000N. what is the acceleration of the jet? what is the force of air resistance acting on the jet?

0 acceleration, 80,000N

if the radius in which an object moves in uniform circular motion is tripled while the speed remains constant the centripetal acceleration is multiplied by a factor of

1/3

what total force will cause an object with a mass of 2kg to gain 5 meters per second every second?

10N

what resultant force will give a 3kg mass an acceleration of 4 m/s2?

12N

Larry's total energy (KE+PE) is 1870 J as he reaches 100m above the ground in a sky diving airplane. what is Larry's gravitational potential energy when he begins to jump at rest from the airplane at an altitude of 900m?

1870 J

suppose that you climb a flight of stairs while carrying a pail that weighs 100N. if the top of the stairs is 3 meters higher than the bottom, how much work has been done by the force that you exert on the pail?

300J

who discovered Newtons first law of motion

Galileo

the fundamental unit of work and energy

Joule

a pendulum moves with the greatest velocity

at the bottom of its swing

an object in motion will stay in what kind of motion as long as the net force acting on it are zero?

constant speed in a straight line (constant velocity) or at rest

a car is going around a banked curve at a high rate of speed. for the car not to skid, in which direction does the frictional force act?

down the plane

A book, weighing 10 Newtons, sits on a table. Which of the following pairs of forces is an action-reaction pair?

force that the book exerts on the table and the force the table exerts on the book

if you increase the distance between two objects by a factor of three, what happens to the force between them?

it reduces to a ninth

the law of inertia states that a moving object will

keep moving if no unbalance force acts on it

a block is sliding on a rough surface with a coefficient of static friction mu s=0.1. the mass of the block is m=10kg, calculate the magnitude of the force of kinetic friction.

less than 10N

kinetic energy is energy that an object possesses because of its

motion

you weigh an object by hanging it from a rope which works by reading the amount of tension. you do this on a moving elevator. under which of the following circumstances would you expect the scale to read more than the actual weight?

moving upward with a constant acceleration

When an arrow is fired from a bow, the arrow keeps moving after it leaves the bow because

no force stops it

Two blocks with the same mass are connected by a string and are pulled across a frictionless surface by a constant force. Will the two blocks move with constant velocity?

no, both will move with a constant acceleration

for a system in simple harmonic motion, what is the time required to complete a cycle of motion?

period

you are pushing a crate rightwards with a mass of 10kg with a force of 150N. the surface is rough, and the frictional force has a magnitude of 100N. the net force on the mass is

rightwards 50N

motion that repeats itself in equal intervals of time

simple harmonic motion

what two factors do you use to describe force?

strength and direction

the recoil or "kick" of a gun that is firing a bullet is a force exerted on the gun by

the bullet

when you step on the gas in your car, the wheels push against the ground and the ground pushes back. the force that makes the car accelerate is exerted by

the ground

work is defined as

the product of the force and the distance the object displaced

a car is going around a banked curve at a high rate of speed. for the car to take the bend successfully, in which direction does the centripetal force acts?

towards the center of the curve

(T/F) the only way to slow down a moving object is to apply a net force to it

true

(T/F) when an object is stationary all of the forces acting on it are balanced

true

a rocket with a mass of 2000kg turns and fires its engine with a thrust of 200,000N. because of this thrust, the rocket must be accelerating...

upward at 100 m/s2

i stretch a rubber band and fling it across the room. when does the rubber band have energy?

when it is stretched and when it is flying

describe your energy at the top of a roller coaster hill, just before you start moving into the big drop. you are currently perfectly still.

you have potential energy