Lower Secondary Science

[Koky462]

Thanks alot, mum_sugoku! I appreciate your help!

[barbie kelly ng]

I am desparately looking for a secondary 1 science tutor and anyone has recommendations. We are staying in Serangoon Central. Thank you very much.

[meimeitan]

Hi Parents and Students


Do u hv the answers for the textbook of ‘Chemistry Matters for GCE O Level’ - third edition?

Thanks.

[cheese]

meimeitan:

Hi Parents and Students


Do u hv the answers for the textbook of 'Chemistry Matters for GCE O Level' - third edition?

Thanks.

Same here. looking for the answers for the text book of \"Chemistry Matters for GCE O Level.
Dun noe any website can provide or can we buy the answer booklet?
Appreciate advice & help.

[Interested]

Hi,


Need help to advise on what are the suitable science assessment or reference book for physic, chemistry and biology for ds in sec 1 ? Is there a different on the type of reference or assessment books that I have to get for ip school. TIA

[Dr.033430Daniel]

A book that I use in my class has a red cover and is called Lower Secondary Science Conceptual Exercises. Author G.S.Cheng. It has fewer mistakes in it than most other books. The student will still need to read his textbook though for the conceptual understanding. This book is almost all problems.

[Interested]

Dr.Daniel:

A book that I use in my class has a red cover and is called Lower Secondary Science Conceptual Exercises. Author G.S.Cheng. It has fewer mistakes in it than most other books. The student will still need to read his textbook though for the conceptual understanding. This book is almost all problems.

:thankyou: Dr Daniel, hopefully I can get from popular.

[red rose]

Hi! Wondering if anyone can help me out with these 2 upper sec Physics problems.


Q1. Tom uses a stopwatch to measure the time between 2 lamp-posts on a car journey. As the car speeds up, 2 consecutive times are 1.2s and 1.0s. Later, he finds out that the lamp-posts are 30m apart.
(a) Calculate the acceleration of the car and its speed at the first lamp-post.
(b) Assuming the same acceleration as found in (a), find the time the car took to travel the 30m before the first lamp-post.

Q2. A juggler throws a ball up in the air with initial speed of 5.00m/s from a height of 1.20m. At the instant the ball reaches its maximum height, the juggler throws up another ball with the same speed and from the same height. At what height will the balls pass each other? (g=10.0m/s2)

Thank you in advance!

[Dr.033430Daniel]

red rose:

Q1. Tom uses a stopwatch to measure the time between 2 lamp-posts on a car journey. As the car speeds up, 2 consecutive times are 1.2s and 1.0s. Later, he finds out that the lamp-posts are 30m apart.
(a) Calculate the acceleration of the car and its speed at the first lamp-post.
(b) Assuming the same acceleration as found in (a), find the time the car took to travel the 30m before the first lamp-post.

For Question 1, part a)
His speed in the middle of the first time interval is 30m/1.2s = 25 m/s.
His speed in the middle of the second time interval is 30m/1s = 30 m/s
To find the acceleration, take change in speed over change in time. The change in speed is 5m/s. The change in time is 0.6s+0.5s = 1.1s. (the amount of time between the middle of the two time intervals). The acceleration is then 5/1.1 = 4.5 m/s^2.

To get the velocity at the moment he passes the first lamp post, take 25m/s to be a final velocity 0.6s later. Use: v= u+at. Solve for u, the initial velocity at the time he passes the first lamp post.

25m/s = u + 4.5(0.6s). u = 22.3m/s

Now with this velocity for part b you can solve using one of the kinematics equations. It will become the final velocity for part b. Assume constant acceleration.

This problem is unusual for secondary level in that it involves realizing that the speed you calculate is in the middle of a time interval. It takes a while to \"see\" this. I used to teach a laboratory class at University in the USA where we did these kind of calculations for falling objects.

[red rose]

Dr.Daniel:

red rose:

Q1. Tom uses a stopwatch to measure the time between 2 lamp-posts on a car journey. As the car speeds up, 2 consecutive times are 1.2s and 1.0s. Later, he finds out that the lamp-posts are 30m apart.
(a) Calculate the acceleration of the car and its speed at the first lamp-post.
(b) Assuming the same acceleration as found in (a), find the time the car took to travel the 30m before the first lamp-post.

For Question 1, part a)
His speed in the middle of the first time interval is 30m/1.2s = 25 m/s.
His speed in the middle of the second time interval is 30m/1s = 30 m/s
To find the acceleration, take change in speed over change in time. The change in speed is 5m/s. The change in time is 0.6s+0.5s = 1.1s. (the amount of time between the middle of the two time intervals). The acceleration is then 5/1.1 = 4.5 m/s^2.

To get the velocity at the moment he passes the first lamp post, take 25m/s to be a final velocity 0.6s later. Use: v= u+at. Solve for u, the initial velocity at the time he passes the first lamp post.

25m/s = u + 4.5(0.6s). u = 22.3m/s

Now with this velocity for part b you can solve using one of the kinematics equations. It will become the final velocity for part b. Assume constant acceleration.

This problem is unusual for secondary level in that it involves realizing that the speed you calculate is in the middle of a time interval. It takes a while to \"see\" this. I used to teach a laboratory class at University in the USA where we did these kind of calculations for falling objects.

Your help is greatly appreciated, Dr Daniel.

If it's not too much to ask, can you help with Q2 too? Thanks and have a good day!