Forces and Motion Flashcards
Why is the gravitational field strength smaller o the moon than on the earth?
The moon has less mass compared to the earth
How do you take measurements to find the speed of the car at the bottom of a slope?
- Place a light gate at the end of the ramp
- Record the time taken using a stopwatch as the car passes through
- Measure the distance of the slope using a ruler
For the experiment to investigate speed of a car, why might a student get different results?
Poor car launch
Friction could slow the car down
Reaction time may cause stopping the stopwatch to be inaccurate
Why must the value of the train be higher than the value calculated?
The train doesn’t travel at a constant speed throughout the journey and could’ve been faster at other stations
Why is the acceleration of a plane not constant even though the engine produces a constant force?
Air resistance acts on the plane causing it to decelerate considering there is a resultant force acting on the aircraft as the speed increases
Why should the airline not use an airplane that has a higher mass and needs a higher speed for landing
Stopping distance is affected by the mass and a faster plane requires a greater distance and as well as does a heavier plane
How do you measure extension?
Measure the length of elastic band without the weights using a ruler then measure then measure length with 12N masses. Subtract the two values to obtain extension.
How does the upward acceleration of balloon change during the first few seconds of the flight of a hot air balloon
The speed increases hence, drag increases which leads to upward acceleration to decrease
How to measure weight
Using a balance
Why would an increase in the impact time decrease the risk of injury
A longer impact time reduces the force on the person for the same change of momentum
What happens as momentum increases all the time?
As momentum increases, velocity increases
SI unit for mass?
Kilograms (Kg)
mx –> x
Divide by 1000
What does it mean for acceleration if there is presumably no air resistance?
Acceleration is 10
How does the graph show that the ball accelerates when it falls?
- Gradient = speed
- Gradient increases as time increases
- Speed increases with time
Factors increasing braking distance
- Poor brake quality
- Increased mass of vehicle
- Increased speed of vehicle
- Road may be wet or icy hence, poor road conditions
Terminal Velocity questions
- At the start, accelerates as speed increases because the force of weight is greater than air resistance
- as the speed increases, force of air resistance acts on the thing which increases and becomes greater than the force of weight hence, reluctant force decreases therefore causing velocity to decrease and the thing to decelerate
- As the thing falls, force of air resistance becomes equal to weight hence, reaching terminal velocity
In the context of terminal velocity, why do lighter objects reach it faster?
- Lighter objects reach terminal velocity faster
- due to a smaller drag force being required
- therefore, it falls slower
What does it mean when reluctant force of something increases or decreases in the context of speed
- When speed decreases, reluctant force decreases
- when speed increases, reluctant force increases
How might protective gear reduce risk of injury to the person?
- Time of impact increases
- Force on person decreases
- Pressure on person decreases
- For the same change in momentum
How to deal with anomalous results?
- Repeat the anomaly
Principal of moments? (2 marks)
- For an object to be in equilibrium,
- Total moments clockwise = Total moments anticlockwise
Define centre of gravity
- The point where the mass of an object is concentrated
