Answer the questions and you will be given a prize.
A car starts from rest and travels for 10 seconds with a constant acceleration of 3.0metre per second squared . The driver then applies the brakes causing a constant negative acceleration of -4.0 metre per second squared . Assuming the brakes are applied for 2.0 seconds:
a.How fast is the car going at the end of braking?
b.How far has the car gone at the end of braking?
Sir, since nobody has tried to answer your questions, I'd like to participate again if you don't mind. :)
ReplyDeletea=acceleration,
u=initial velocity,
v=final velocity,
t=time for the velocity change,
s=displacement
a. v= u+at
After 10 seconds' travel, v1= 0+(3*10)=30m/s
After 2 seconds' brake, v2= 30+((-4)*2)=22m/s
The car is going at 22m/s at the end of braking.
b. s= 1/2 (u+v)t
After 10 seconds' travel, s1= 1/2 (0+30)*10 = 150m
After 2 seconds' brake, s2= 1/2 (30+22)*2 = 52m
So, 12 seconds' travel s3= s1+s2 = 202m
The car has gone 202m at the end of braking.
Hi michan. I cannot verify your answer now as I don't have a pen and a calculator with me because I am in a cyber cafe waiting for someone until 9.00 pm.I shall verify as soon as I can.
ReplyDeleteSo sorry michan, I will give you another try.
ReplyDeleteAfter your appeal, I double checked and found out that you were right. Hiyo, it means another price for you. haaaaaaaaaaa
ReplyDeleteThank you very much, Sir. After I had posted my answers last week, my heart beat for 4 days with a constant acceleration while waiting for your reply. After you told me they were wrong, it braked causing a constant negative acceleration for 4 days (Thank God it didn't stop...). Now that you confirmed there were actually no mistakes, my heart can finally beat normally again, hee hee.
ReplyDeleteHaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa i am now laughing with an acceleration of 10 meter per second squared after reading your comments.
ReplyDelete