physics help!!!!!!!!

[highly_ambitious]

hey guys i need your help for some of the physics questions. I'm dumb in phy. so plzzz help me.

1. A cyclist is free-wheeling down a long straight hill. The times between passing successive kilometers posts are 100 seconds and 80 seconds. Assuming his acceleration is constant, find the acceleration.

2. A train is slowing down with a constant deceleration. It passes a signal at A, and after successive intervals of 40 seconds it passes B and C, where AB = 1800m and BC=1400m. Find :
a. How fast is the train moving when it passes A?
b. How far from A does it come to stop?

I'll be very grateful to have the replies to the answers.so plz reply as soon as possible

[astarmathsandphysics]

hey guys i need your help for some of the physics questions. I'm dumb in phy. so plzzz help me.

1. A cyclist is free-wheeling down a long straight hill. The times between passing successive kilometers posts are 100 seconds and 80 seconds. Assuming his acceleration is constant, find the acceleration.

2. A train is slowing down with a constant deceleration. It passes a signal at A, and after successive intervals of 40 seconds it passes B and C, where AB = 1800m and BC=1400m. Find :
a. How fast is the train moving when it passes A?
b. How far from A does it come to stop?

I'll be very grateful to have the replies to the answers.so plz reply as soon as possible

1.Use suvat twice

s=1000
u=?
v=?
a=a
t=100

s=ut+1/2at²
1000=100u+5000a   (1)

s=2000
u=?
v=?
a=a
t=180

s=ut+1/2at²
2000=180u+16200a  (2)

Now solve (1) and (2) (2/412)-1.8(1) gives 200=7200a so a=1/36m/s²

[astarmathsandphysics]

2. A train is slowing down with a constant deceleration. It passes a signal at A, and after successive intervals of 40 seconds it passes B and C, where AB = 1800m and BC=1400m. Find :
a. How fast is the train moving when it passes A?
b. How far from A does it come to stop?

I'll be very grateful to have the replies to the answers.so plz reply as soon as possible

a)Use suvat twice again

For Ab

s=1800
u=u
a=a
v+?
t=40

s=ut+1/2at²

1800=40u+800a   (1)

For AC

s=3200
u=u
a=a
v+?
t=80

s=ut+1/2at²
3200=80u+3200a  (2)

(2)-2*(1) -400=1600a so a =-1/4m?s²

b)3200=80u+3200a from part a) and a=-1/4 so u=(3200-3200*-1/4)/80=50m/s

v²=u²+2as

0=50²+2*-1/4*s so s=5000m

[highly_ambitious]

sir, but the answer is s=5000m .

[astarmathsandphysics]

I corrected the above p[ost