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P5: Quiz 13 – Answers
P5: Quiz 13 – Answers
1)
a) Air resistance/ drag and friction
b) Increase – as the velocity of the car increases, the resistive forces increase
2) The terminal velocity of an object is the maximum velocity that an object will travel at
3)
a) The acceleration rate is the greatest at the start. We can tell this because the velocity time graph is the steepest at the start and a steeper line on a velocity time graph means a faster acceleration rate
b)
i) Weight
ii) Air resistive/ drag
c) 13 seconds (±1)
d) Weight and air resistance/ drag equal each other when the ball is at its terminal velocity (weight = air resistance)
e) 0 N or zero
4)
a) Yes – the weight of the two objects will be the same
b) Object B is less streamlined, which means that object B will always have greater resistive forces (air resistance/ drag) for all velocities compared to object A. This means that for object B the resistive forces will equal the weight at a lower velocity, thus meaning that the terminal velocity of object B is lower than the terminal velocity of object A
5)
a) Greater when the parachute is open
b)
i) 60 seconds (±5)
ii)140 seconds (±5)
iii) 180 seconds (±5)
iv) When the sky diver opens his parachute, the resistive forces (air resistance/ drag) increases. His weight stays the same, so an increase in resistive forces from opening the parachute results in a huge resultant force upwards. The sky diver will accelerate in the direction of the result force (he will accelerate upwards), which will cause his velocity to decrease
a) Air resistance/ drag and friction
b) Increase – as the velocity of the car increases, the resistive forces increase
2) The terminal velocity of an object is the maximum velocity that an object will travel at
3)
a) The acceleration rate is the greatest at the start. We can tell this because the velocity time graph is the steepest at the start and a steeper line on a velocity time graph means a faster acceleration rate
b)
i) Weight
ii) Air resistive/ drag
c) 13 seconds (±1)
d) Weight and air resistance/ drag equal each other when the ball is at its terminal velocity (weight = air resistance)
e) 0 N or zero
4)
a) Yes – the weight of the two objects will be the same
b) Object B is less streamlined, which means that object B will always have greater resistive forces (air resistance/ drag) for all velocities compared to object A. This means that for object B the resistive forces will equal the weight at a lower velocity, thus meaning that the terminal velocity of object B is lower than the terminal velocity of object A
5)
a) Greater when the parachute is open
b)
i) 60 seconds (±5)
ii)140 seconds (±5)
iii) 180 seconds (±5)
iv) When the sky diver opens his parachute, the resistive forces (air resistance/ drag) increases. His weight stays the same, so an increase in resistive forces from opening the parachute results in a huge resultant force upwards. The sky diver will accelerate in the direction of the result force (he will accelerate upwards), which will cause his velocity to decrease
Questions
1) The diagram below shows a car travelling towards the right.
1) The diagram below shows a car travelling towards the right.
a) There are two resistive forces that act in the opposite direction to the direction of travel. What are these two resistive forces?
b) Do the resistive forces increase or decrease as the velocity of the car increases?
2) What is meant by the term terminal velocity?
3) The velocity time graph below is for a ball after it has been dropped out of a helicopter.
b) Do the resistive forces increase or decrease as the velocity of the car increases?
2) What is meant by the term terminal velocity?
3) The velocity time graph below is for a ball after it has been dropped out of a helicopter.
a) Is the acceleration rate of the ball the greatest at the start or at the end? Explain how you can tell this from the velocity time graph above.
b)
i) Which force is always constant whilst the ball is travelling towards the ground?
ii) Which force increases overtime as the ball travels towards the ground?
c) At what time does the ball reach its terminal velocity?
d) When the ball is at its terminal velocity, what two forces balance out?
e) What is the resultant force when an object is at its terminal velocity?
4) Let’s suppose that we have two objects (A and B) that have the same mass. Object A is more streamlined than object B.
a) Will the weight of both of the objects be the same?
b) Explain why object B will have a lower terminal velocity than object A.
5) We are now going to have a look at a sky diver’s velocity as he jumps out of a plane and opens his parachute.
a) Would the resistive forces acting on a sky diver be greater when he is travelling at 30 m/s with the parachute in his backpack or when he is travelling at 30 m/s when his parachute is open?
b) The graph below is a velocity time graph for a sky diver jumping out of a plane.
b)
i) Which force is always constant whilst the ball is travelling towards the ground?
ii) Which force increases overtime as the ball travels towards the ground?
c) At what time does the ball reach its terminal velocity?
d) When the ball is at its terminal velocity, what two forces balance out?
e) What is the resultant force when an object is at its terminal velocity?
4) Let’s suppose that we have two objects (A and B) that have the same mass. Object A is more streamlined than object B.
a) Will the weight of both of the objects be the same?
b) Explain why object B will have a lower terminal velocity than object A.
5) We are now going to have a look at a sky diver’s velocity as he jumps out of a plane and opens his parachute.
a) Would the resistive forces acting on a sky diver be greater when he is travelling at 30 m/s with the parachute in his backpack or when he is travelling at 30 m/s when his parachute is open?
b) The graph below is a velocity time graph for a sky diver jumping out of a plane.
i) At what time does the sky diver reach his first terminal velocity?
ii) At what time does the sky diver open his parachute?
iii) At what time does the sky diver reach his second terminal velocity?
iv) Explain why the velocity of the sky diver decreases after he opens his parachute.
ii) At what time does the sky diver open his parachute?
iii) At what time does the sky diver reach his second terminal velocity?
iv) Explain why the velocity of the sky diver decreases after he opens his parachute.