atutor2001:

tianzhu:

........


In P6 science, students learnt that friction helps to reduce slipping and sliding. Friction between the soles of the shoes and the ground allows us to walk and run. For wheels rolling on a road, friction (traction) prevents them from slipping. Therefore, applying powder on the surface may cause the car to move a shorter distance as it causes slipping.

Hence option (4) is out.

Best wishes

Hi

My view differ from yours. If a surface is frictionless, the car will move indefinitely (i.e. there is no retarding force). All moving object comes to a stop because of friction. Without friction, a moving will continue moving indefinitely. A car skidding on snow surface can continue moving for a long distance. However, the driver has no control of the direction.

Friction is purposely created in shoes and wheels for \"control\". If we are able to control e.g. ice skating, we can move effortlessly for great distance with lesser effort.

Hi

if u try cycling over a pile of sand, u can feel this effect
can u cycle easier over a pile of sand or normal road surface?
powder same ya?

however if the object had no wheels, like a box, and with just a few grain of sand
the sand wud have acted like ball bearings to make it move further.
if the box had to move over a pile of sand, then it would move lesser

same same for powder, ya?

also
for option 3, where car is made lighter
if car is made of paper, then it is useless for distance

so maybe it is not a very good question?

maybe

INNOVATE:

Chongfu's golden era was btw the v late 1990s and 2007.


During the above period, the mean aggregate was approx 224-226, 80% qualified for express and slightly more than 30% qualified for SAP ie 250 and above. The school had produced no less than 8 PM's Book Prize winners for bilingualism. In those yrs, it set the standard for good neighbourhood schools.

The academic standard has gone down of late. Just hope that the turnaround can happen soon.

Hi Innovate,

any idea how was the PSLE results for 2008, 2009, 2010 (comapred to the earlier yrs) ?