Motion and forces (Extended response)

Question 1

A trolley, ramp and two light gates are being used to investigate the relationship between the acceleration of a trolley on a slope and the angle that the slope makes with the horizontal.

Describe a simple investigation to determine how the acceleration of the trolley depends on the angle of the slope.

Answer 1

I will start with the ramp at an angle of 10° and roll the trolley down the slope from the same starting position each time.
The mass of the trolley needs to be kept constant, and a suitable value would be 500 g.
I will then increase the ramp angle by 5° each time until I have at least 6 readings.
I will repeat readings to check for accuracy and precision.

The speed of the trolley at each light gate is calculated using the equation: speed = distance ÷ time, where the distance recorded is the length of the card that passes through the light gates.
The acceleration of the trolley is calculated by finding the difference in the speed values at the two light gates and then dividing this by the time it takes the trolley to pass between the gates.

I would expect the acceleration of the trolley to increase as the angle increases, although the relationship may not be linear.
This is because as the slope angle increases, you increase the component of the trolley’s weight that is acting down the slope, which is the force responsible for the trolley’s acceleration.

Question 2

The distance taken for vehicles to stop on roads depends on a number of factors. Discuss what these factors are and how they affect stopping distance.

Answer 2

-reaction times and thinking distance
as reaction time increases so does thinking distance
reaction time is the time between seeing the hazard and applying a force to the brakes

-speed of car
affecting thinking and braking distance
more speed means a greater distance is covered when thinking and braking compared with a lower speed

-alcohol, drugs, or tiredness
affecting reaction times and thinking distance
both will increase if the drivers are under the influence of these
they will be less alert

-condition of tyres
bald tyres mean greater braking distance
as there will be less grip

-condition of road
icy/wet
resulting in less grip
causes a greater breaking distance

-mass of car/number of passengers
increases braking distance at a given speed due to greater inertial mass
/greater constant force needed over a longer time to stop