Q&A - PSLE Science

[Muffins]

ruyu:

Tang:

[quote=\"mummyjoyce\"]
1 is definately out; so best choice is 3

Hello,

A is the changed variable.

D is the result you measure (so cannot be kept constant.

So variables to be kept constant are B and C. Hence no correct answer provided.

no it cant be b as they did not say that if the texture of the ramp affected the distance travelled by the ball. So you will have to change the length of the ramp. So the answer is 1.[/quote]Hi ruyu

Sorry to intrude, but the question actually states that we are looking for the slope of the ramp affects the experiment. The only way that the gradient, or slope, would be affected is if the number of books is changed, so the number of books cannot remain constant. If you follow that rule, then 1, 3 and 4 will automatically be eliminated. So the obvious answer would be 2. However, since the distance of the ball must be affected by the slope of the ramp, the most correct answer would be B and C, therefore classifying this question as incorrectly set... :celebrate:

[Sun_2010]

[quote=\"Muffins]

Hi ruyu

Sorry to intrude, but the question actually states that we are looking for the slope of the ramp affects the experiment. The only way that the gradient, or slope, would be affected is if the number of books is changed, so the number of books cannot remain constant. If you follow that rule, then 1, 3 and 4 will automatically be eliminated. So the obvious answer would be 2. However, since the distance of the ball must be affected by the slope of the ramp, the most correct answer would be B and C, therefore classifying this question as incorrectly set... :celebrate:[/quote]

Totally agree...

[Muffins]

Sun_2010:

Muffins:

Hi ruyu

Sorry to intrude, but the question actually states that we are looking for the slope of the ramp affects the experiment. The only way that the gradient, or slope, would be affected is if the number of books is changed, so the number of books cannot remain constant. If you follow that rule, then 1, 3 and 4 will automatically be eliminated. So the obvious answer would be 2. However, since the distance of the ball must be affected by the slope of the ramp, the most correct answer would be B and C, therefore classifying this question as incorrectly set... :celebrate:

Totally agree...

Thanks!

[Tang]

Muffins:

ruyu:

[quote=\"Tang\"]

Hello,

A is the changed variable.

D is the result you measure (so cannot be kept constant.

So variables to be kept constant are B and C. Hence no correct answer provided.

no it cant be b as they did not say that if the texture of the ramp affected the distance travelled by the ball. So you will have to change the length of the ramp. So the answer is 1.

Hi ruyu

Sorry to intrude, but the question actually states that we are looking for the slope of the ramp affects the experiment. The only way that the gradient, or slope, would be affected is if the number of books is changed, so the number of books cannot remain constant. If you follow that rule, then 1, 3 and 4 will automatically be eliminated. So the obvious answer would be 2. However, since the distance of the ball must be affected by the slope of the ramp, the most correct answer would be B and C, therefore classifying this question as incorrectly set... :celebrate:[/quote]
Hello,

By changing the number of books, we change the slope of the ramp, which is the changed variable.

By changing the length of the ramp, the slope of the ramp is changed. But the distance travelled by the toy car is also changed. Hence there are 2 changed variables instead of one and the experiment will not be a fair one.

To illustrate with an example. Keeping the slope constant at 30 degree, we will expect the ball to move the same distance. But by using different lengths for the ramp (with the number of books changed), the one with a longer ramp will have a higher potential energy and the distance the ball moved will also be further.

Have a nice weekend.

[ruyu]

Tang:

Muffins:

[quote=\"ruyu\"]
no it cant be b as they did not say that if the texture of the ramp affected the distance travelled by the ball. So you will have to change the length of the ramp. So the answer is 1.

Hi ruyu

Sorry to intrude, but the question actually states that we are looking for the slope of the ramp affects the experiment. The only way that the gradient, or slope, would be affected is if the number of books is changed, so the number of books cannot remain constant. If you follow that rule, then 1, 3 and 4 will automatically be eliminated. So the obvious answer would be 2. However, since the distance of the ball must be affected by the slope of the ramp, the most correct answer would be B and C, therefore classifying this question as incorrectly set... :celebrate:

Hello,

By changing the number of books, we change the slope of the ramp, which is the changed variable.

By changing the length of the ramp, the slope of the ramp is changed. But the distance travelled by the toy car is also changed. Hence there are 2 changed variables instead of one and the experiment will not be a fair one.

To illustrate with an example. Keeping the slope constant at 30 degree, we will expect the ball to move the same distance. But by using different lengths for the ramp (with the number of books changed), the one with a longer ramp will have a higher potential energy and the distance the ball moved will also be further.

Have a nice weekend.[/quote]
darn i got do this question before and she say answer 1...... knew she was bad very bad. For one question on the dam question, when asked what has more gravatational potential engergy she choose the water which was gushing through the turbines instead of the water behind the dam. Why must we get a teacher like this in P6? :stupid:

[Nebbermind]

the books MUST NOT change as this WILL CHANGE the Potential Energy of the car.


Since this cannot change, the only way to change the angle of the slope is by increasing or decreasing the length of the ramp. Therefore it’s A & C.

[MOE Hater]

Nebbermind:

the books MUST NOT change as this WILL CHANGE the Potential Energy of the car.


Since this cannot change, the only way to change the angle of the slope is by increasing or decreasing the length of the ramp. Therefore it's A & C.

Ok lets take it ur way:

If the books remain the same it means the height remains the same , the PE remains the same so the KE of the car (converted from PE) will also be the same. Hence the ball's ke will be the same and so should move the same distance.

So this means in this expermiment, the distnace travelled by the ball will be the same irrespective of the angle.

???
Is that what you want to say?

[Nebbermind]

MOE Hater:

Ok lets take it ur way:


If the books remain the same it means the height remains the same , the PE remains the same so the KE of the car (converted from PE) will also be the same. Hence the ball's ke will be the same and so should move the same distance.

So this means in this expermiment, the distnace travelled by the ball will be the same irrespective of the angle.

???
Is that what you want to say?

No, coz the ball can only move in the horizontal direction while the car coming down the slope will have horizontal and vertical velocity. Hitting the ball flatly from the top will not cause it to move forward.

[ruyu]

Nebbermind:

MOE Hater:

Ok lets take it ur way:


If the books remain the same it means the height remains the same , the PE remains the same so the KE of the car (converted from PE) will also be the same. Hence the ball's ke will be the same and so should move the same distance.

So this means in this expermiment, the distnace travelled by the ball will be the same irrespective of the angle.

???
Is that what you want to say?

No, coz the ball can only move in the horizontal direction while the car coming down the slope will have horizontal and vertical velocity. Hitting the ball flatly from the top will not cause it to move forward.

jeez finally someone to support me.........

[MOE Hater]

Nebbermind:

the books MUST NOT change as this WILL CHANGE the Potential Energy of the car.


Since this cannot change, the only way to change the angle of the slope is by increasing or decreasing the length of the ramp. Therefore it's A & C.

The greater the angle of inclination of the ramp, the greater the distance travelled by the ball. However, this is not a direct relationship. The greater inclination increases the car's potential energy. This is converted to more kinetic energy when released, and when it hits the ball, the ball would in turn possess greater kinetic energy. This is what enables it to travel a greater distance. So, in conclusion, the potential energy of the car MUST change for the set-up to work.