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1) Newton’s first law states that an object will remain at rest or in uniform motion (constant speed) in a straight line unless an external force acts on the body. In other words, when a body is at rest or moving at constant speed in a straight line (constant velocity) , straight away you should know it is Newton’s first law . Next you must know these 3 basics concepts about 1st law: – forces acting on the body are balanced – net force / resultant force acting on the body is zero – there is no acceleration. 2) Newton’s second law states that when a net force (resultant force) acts on a body , it will cause an acceleration on the body (accelerating or decelerating). Basically F = ma where F is the net or resultant force in N,m is the mass in kga is the acceleration in ms-2 In other words, when a body is moving faster or slower (or going round a bend), you should know its Newton’s second law . Next you must know these 3 basic concepts about 2nd law: – forces acting on the body are not balanced – there is a net force / resultant force acting on the body – there is an acceleration (accelerating of net force is in the direction of motion, or decelerating if the net force is opposite to the direction of motion)

Instead of the usual finding of potential difference across a component, in this question, you are required to find the p.d. across two points on the two separate branches. If you can relate the river system to the DC circuit, it will help in solving the last part. View the video tutorial

Do you understand why there is a potential difference between P and Q? What if you are to find the potential difference between P and Q? There is a shortcut to getting the answer for this MCQ, but watch the whole video to understand the concepts fully and find the value of the potential difference. Answer: Option D Video the explanation Another question with similar concept: 2012PPp2q07 https://www.sgphysicstuition.com/post/2012ppp2q07-find-the-p-d-across-a-and-c

Prefixes are used to denote very large or small physical quantities . It is important that you know all these prefixes well.

Light and sound are both waves. So both carry energy from one place to another. Light , which is part of the electromagnetic spectrum, is a transverse wave , It can travel through a vacuum at speed 3.0 x 108 m/s. As the light travels from an optically less dense medium (air) to an optically denser medium (liquid or glass) , the light undergoes refraction and bends towards the normal due to a decrease in speed . Light: Optically less dense medium to denser medium:  – speed decreases – wavelength shorter – frequency remains constant Sound is a longitudinal wave . It requires a medium to pass through and it cannot pass through a vacuum . Opposite to light, as the sound travels from a less dense medium (air) into a denser medium (water or solid) , the speed increases . Sound: Less dense medium to denser medium: – speed increases – wavelength longer – frequency remains constant Refers to the image below to understand how the waves behave in different mediums.

To do similar questions, it is important to know the 3 rays which have rules to follow in order to locate the image. Look through the video to learn the concepts and hopefully you can do similar questions in future.

In this post, we will be going to the basics of setting up the retort stand and pendulum experiment. Most probably, this will be the first experiment which you will perform in the lab. Let’s start with the setting up the retort stand, boss and the clamp. Next we will take a look at how you set the up the apparatus for the pendulum experiment.

Refer to the video below for the setting up of the apparatus. Why do you need a variable resistor (rheostat)? Without the variable resistor, you will have only one set of current I and potential difference V readings. Using the formula R = V/I, you are able to find the unknown resistor. But this method is not so accurate . Hence, to make it more accurate, we include a variable resistor to control the size of the current through the circuit. Thus having different readings of the potential difference V across the unknown resistor . Instead of just one set of readings of I and V, we now have about 5 sets. This allows us to plot a graph of V against I. By finding the gradient of the best fit line , we are able to find the resistance more accurately. [gradient = V / I = R, hence the gradient of V-I graph represents resistance R] For pure metallic conductor , like the fixed resistor R, it obeys the Ohm’s Law , hence it is an ohmic conductor. From the graph, the current I flowing the conductor is directly proportional to potential difference V across the conductor, provided physical conditions like temperature remains constant. [the graph is a straight line with constant gradient, and passes through the origin]