OCR Physics A-Level A Module 3 - Forces and motion Complete Questions with Verified detailed Answers

▪ What is speed? - AnsDistance per unit time ▪ What is displacement? - AnsDistance moved in a particular direction from a reference point ▪ What is velocity? - AnsDisplacement per unit time ('speed in a given direction') ▪ What is acceleration? - AnsChange in acceleration per unit time ▪ Equation for average speed? - Anstotal distance / time taken ▪ Equation for average velocity? - Anstotal displacement / time taken ▪ Equation for acceleration? - Anschange in velocity / time taken ▪ What's the gradient on a displacement-time graph? - AnsThe velocity ▪ What's the area under a displacement-time graph? - AnsNothing ▪ What's the gradient on a velocity-time graph? - AnsAcceleration ▪ What's the area under a velocity-time graph? - AnsDisplacement ▪ What are the 5 suvat equations? - Ansv = u + at s = (u + v)t/2 s = ut + 1/2 at^2 v^2 = u^2 + 2as s = vt - 1/2 at^2 ▪ What is free fall? - AnsThe acceleration of a body under the action of a gravitational field, ignoring air resistance and buoyancy. ▪ Why do objects of different masses fall at different rates? - AnsThe force on a heavier object will be greater (w = mg), but acceleration is inversely proportional to mass (a = F/m). ▪ Describe the electromagnet method of measuring g - AnsAn electromagnet /just/ supports a steel ball. When the current through the electromagnet is switched off, the ball starts to fall, and simultaneously a timer is triggered. The ball falls onto the trapdoor and the timer stops. The distance, s, fallen can be measured with a ruler, and the time, t, is given by the timer. ▪ The experiment should be repeated several times to find a mean value for t. More readings could be taken at different heights. ▪ What are problems with the electromagnet method of measuring g? - Ans- If the current is too high, there will be some delay before the ball drops and after the clock is triggered. - If the distance is too large, or the ball too small, air resistance may have a significant effect as the ball may reach terminal velocity - The distance must be accurately measured from the bottom of the ball ▪ What's thinking distance? - AnsThe distance the car travels between the driver seeing the hazard and applying the brakes ▪ What's braking distance? - AnsThe distance the car travels between the driver applying the brakes and the car stopping ▪ What is total stopping distance? - Ansthinking distance + braking distance ▪ What factors can increase thinking distance? - AnsHigher speed, tiredness, drugs, distractions, age of driver ▪ What factors can increase stopping distance? - AnsHigher speed, road conditions (e.g. rain/ice), condition of brakes, condition of tyres, mass of car (e.g. more people/lu