Physics

Centripetal acceleration for the smaller circle is _________ (when the velocity is constant in both the big circle and the large circle)

greater

In a circus, a man hangs upside down from a trapeze, legs bent over the bar and arms downward, holding his partner. It is harder for the man to hold his partner when a)when the partner hangs straight down and is stationary (b)when the partner is swinging through the straight-down position (c)Same effort in both cases

when the partner is swinging through the straight-down position.

𝑇𝑜𝑡𝑎𝑙 𝑐ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑚𝑒𝑐ℎ𝑎𝑛𝑖𝑐𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑓 𝑡ℎ𝑒𝑠𝑦𝑠𝑡𝑒𝑚

(∆𝑬)=∆𝑲𝑬+∆𝑷𝑬 =0 (Because ∆𝑲𝑬=−∆𝑷𝑬)

DOES NOT DEPEND ON THE PATH TAKEN BY THE OBJECT

CONSERVATIVE FORCE

The wheel of a car has a radius of 0.29 m and is being rotated at 830 revolutions per minute (rpm) on a tire-balancing machine. What is the time period T of the wheel?

Find x seconds it takes for 1 revolution

non-conservative forces

Eg1: Work done by force of friction depends only on the length of the path covered. Eg2: Force of tension Eg3: Push or pull by a person Eg4: Air resistance

conservative force examples

Ex:1 Work done by force of gravity depends only on the height from the ground and not on the path taken to reach that height. Ex2: Work done by spring/elastic force depends only how much the spring is compressed or stretched. Doesn't care if it is stretched or compressed.

Consider a man standing at the pole and a man standing at the equator. who has the larger centripetal acceleration

Man at the equator. because a bigger velocity has a bigger centripetal acceleration

unit of work

N.mor Joule (J)

DEPENDS ON THE PATH TAKEN BY THE OBJECT

NON-CONSERVATIVE FORCE

Is velocity constant in uniform circular motion?

No, velocity is speed with direction the direction here is changing

Forces acting on the man when he is moving up the slope with a rough surface with constant acceleration. Is system at equilibrium

No. there is an acceleration

A man holds a rope which causes a model airplane (with mass 𝒎) flying at a constant speed along a circlular path that is parallel to the ground. If the airplane were to be more massive, then the force required to keep it moving at the same speed, with the same radius, would speed= same radius= same mass= changes

The force would increase

For every conservative force, we can define a corresponding potential energy.

The gain in KE is at the cost of PE of the conservative system, and vice versa. ∆𝑲𝑬=−∆𝑷𝑬=𝐖

A man holds a rope which causes a model airplane (with mass 𝒎) flying at a constant speed along a circular path that is parallel to the ground. Compare the tension in the rope of length 𝒓 for speed 𝒗𝟏 and 𝒗𝟐, if 𝒗𝟏> 𝒗𝟐.

The tension must be higher on the rope if the plane moves at a faster velocity, therefore the answer is v1

A car is traveling around a curve at a steady 45 mph. What is the direction of the car's acceleration?

The vector of acceleration is inward because centripetal acceleration always points inward to the circle

The time required for the object to travel once around the circle.

Time Period (T) of the motion

the motion of an object traveling at a constant (uniform) speed on a circular path.

Uniform circular motion is

The wheel of a car has a radius of 0.29 m and is being rotated at 830 revolutions per minute (rpm) on a tire-balancing machine. Determine the speed (in m/s) at which the outer edge of the wheel is moving.

Use formula V= 2(pi)r/ T

along a curve... There is no motion of the car along the radial direction, but only along the tangential direction.

aka no up or down, just side to side

An object in circular motion is always changing direction. this causes the velocity to change hence there must be

an acceleration

If the static frictional force is insufficient, given the speed and the radius of the turn, the car will skid off the road. what is an example of this

an icy road which offers lower force of friction is unsafe

However, the Moon revolves around the Earth along an ELLIPTICAL path. Along any part of the orbit the Earth does

both positive and negative work

A force is non-conservative when the work it does on a moving object is _____________ on the path between the object's initial and final positions.

dependent

The forces that are perpendicular to the ground, (and hence perpendicular to the motion in this case), do not play any role in the motion of the object in the horizontal direction. Hence, the gravitational force and the normal force ________ play a role in keeping the car along the curved path

do not

The reliance on friction can be _____________________ for a given speed, however, if the curve is banked at an angle relative to the horizontal, much in the same way that a plane is banked while making a turn.

eliminated completely

A man holds a rope which causes a model airplane (with mass 𝒎) flying at a constant speed along a circlular path that is parallel to the ground. If the airplane were to move faster, the force required to keep it moving with the same radius would speed= faster radius = same mass- same

force would increase

A force is conservative when the work it does on a moving object is _____________ of the path between the object's initial and final positions

independent

If𝝁𝒔for road on a dry day = 0.5,𝝁𝒔 for the same road on an icy day is ____

less than 0.5

If the force has a component in the direction opposite to the displacement, then the work done by that force is

negative

If the object does not move, the force acting on the object does _____ work!!

no

Other things being equal, would it be easier to drive at high speed around an unbanked horizontal curve on the moon than to drive around the same curve on the earth?

no

Is the principle of conservation of mechanical energy obeyed if•An object moves uphill with an increasing speed.

no, because you are adding KE and PE with conservative energy, KE is basically opposite of PE

If the object is speeding up or slowing down, there is a parallel component of the acceleration. in uniform circular motion, speed is constant so there will not be

parallel acceleration, but there is always a perpendicular acceleration aka centripetal acceleration

If the force has a component in the direction of the displacement, then the work done by that force is

positive

The work done to push a car is the same whether the car is moved north to south or east to west, provided that the amount of force used and the distance moved are the same. Since work does not convey directional information, it is a __________ quantity.

scalar

man holds a rope which causes a model airplane (with mass 𝒎) flying at a constant speed along a circular path that is parallel to the ground. What is causing the centripetal force?

several other forces. in this case force of tension is causing centripetal force

When a car moves at a steady speed around a curve, the centripetal force keeping the car on the curve comes from the

static friction between the road and the tires keeps a car along an unbanked curve. It is static, rather than kinetic friction, because the tires are kept from slipping in the radial direction.

When a car travels without skidding around an unbanked curve, the ______________________ between the tires and the road provides the centripetal force.

static frictional force

A car is traveling around a curve at a steady 45 mph. Is the car accelerating?

yes, because the object is changing its direction so there is an acceleration not making it go faster but allowing it to change cars direction

If there is no component of force along the direction of displacement, work done by that force is

zero

if the box is at rest or moving at constant velocity along a particular axis, net force is________ along that axis. If it is speeding up or slowing down, then net force is ______

zero along that axis. ma

If the Moon revolves around the Earth in a CIRCULAR path of fixed radius with constant speed, along any part of the orbit the Earth does

zero work

If the distance s is zero, the work is________ even if a force is applied.

zero,