Mechanics

Is velocity always 0 when it strikes the ground?

No

Steps of this question

Distance in 0.4m

Velocity of Q

Distance in 1.1m-by speed=distance/time

Add times together

Velocity time graph tips

W

State one limitation of the model apart from ignoring air resistance that will affect the accuracy of tension

Pulley system

Include weight of rope

Suggest one refinement that would make the model more realistic

Vertical motion

Use a more accurate value of g-only if g is originally 10

Allow for wind effects

In reality the stone will not move freely under gravity and will be subject to air resistance How would this affect the initial velocity

Vertical motion

Greater

State one limitation of the model which could affect the acceleration and speed

Train moving-uniform acceleration

Horizontal motion

Train wont move with constant acceleration

Draw increasing distance on a distance time graph

Draw constant speed on a distance time graph

Draw decreasing speed on a distance time graph

Give 2 reasons why distance is likely to be different

Horizontal motion

Bumps in the road affect the trailer

Resistance differs

Refinement to model of stone in air

Vertical motion

Include the dimensions of the stone

Steph for part b only

Find final velocity of Q-which is the initial velocity of P

Find the distance P moves With this velocity-BUT WITH G AS ACCELERATION AS Q doesn’t rebound so tension is non existent or GOES TO INSTANTANEOUS rest and with that velocity u found as initial velocity now bc it was final for Q-

Add the 2h and the h-for the distance Q moves bc P moves the exact same amount- and add the distance you calculated for P as well-the one u used the initial velocity for-

When is there no tension?

No tension when not connected

What does a light system mean?

Tension is equal

What does inextensible suggest?

Equal acceleration

What does a smooth pulley suggest?

Acceleration is equal

When the string breaks what changes?

Acceleration

As system is now in free fall

Limitation of using resistance for motion of a car

Air resistance can vary depending on speed so wont be constant

Normal reaction what do you do

Multiply the number by g

Improvements to pulley system

Doesn’t take into account mass of string

What affects acceleration in terms of rope

Rope being light

What affects the tension in a pulley system

Pulley not being smooth

Limitation of modelling balls as particles

Distance in terms of h

Distance it falls would not be exactly h

Steps of this question;

find the time taken by P to hit the pulley from the instant when P is released.

Time Q to hit floOr

Speed for Q to hit floor

Time for P to hit the pulley-after Q hits the floor- speed= distance divided by time

Add times together

Use coordinates for a velocity time graph shape might be easier

What does a negative velocity mean?

Opposite direction

When can you not use g for acceleration

If the question doesnt say freely under gravity

3

Refinement to suvat model

Remember all

Include air resistance

Use a more accurate value for g

Take into account wind effects

In reality the stone will not move freely under gravity and will be subject to air resistance.

(d) Explain how this would affect your answer to the initial velocity and give a reason

U would be greater.

As air resistance would slow the object in motion down

In a displacement SUVAT equation What do you take the initial velocity as positive or negative?

If upwards is taken as positive

Positive