Number 4 should be D, not B. Reason being is that you want to have the object stationary (not moving). If so, then the third force must be X and Y to the right.
You are mistaken. The forces X and Y shown are 'to the right' so to balance these forces, the opposing force must be to the left. Think about it again.
Remember it's a displacement-time graph. It is not showing the velocity directly. The gradient of the graph gives the velocity and the gradient of a straight line is a constant, hence the runner is moving at constant speed.
I have a question. For no. 52, they never said which direction into the paper it was going. Thus, the direction could vary between two answers. Unless they said if it was heading upwards or downwards into the paper. Plz help me to understand which direction it is going. For.they never said
Ok... whenever the phrase 'into the paper' is used it means perpendicular or at right angle to the plane of the paper; not parallel to it. So if the paper is on the desk then into the paper means it's coming down into the paper.
During radioactive decay the amount of radioactive substance decreases by a half every time one half-life passes. To reach one-eight of its original value a sample must pass through 3 half-lives. So if 1 half-life is 20 units, 3 half-lives must be 60 units.
