Force and Motion I

Question 4:A car is driven from rest and accelerated at 4 m s–2 for 8 s along a straight road. Th e car is driven at the constant velocity for 20 s and then its brakes are applied. Th e car reduces its velocity at the rate of 2 m s–2 till it stops. Sketch … Read more

Question 1:How do you determine(a) velocity from a graph of displacement against time?(b) acceleration from a graph of velocity against time?(c) displacement from a graph of velocity against time? Answer:(a) For displacement-time graph: Velocity = gradient of the graph(b) For velocity-time graph: Acceleration = gradient of the graph(c) For velocity-time graph: Displacement = area under … Read more

Question 1:Explain the difference between(a) distance and displacement (b) speed and velocity Answer:(a)(b) Question 2: A car moving along a straight road at a velocity of 30 m s–1 reduces its velocity at a constant rate until it stops after 5 s. What is the acceleration of the car? Answer:$$ \begin{aligned} & u=30 \mathrm{~ms}^{-1} \\ & … Read more

Diagram 5.1 (a) shows a boy skating down a ramp from position (X). Diagram 5.1 ((b)) shows the velocity-time graph of the boy from (X) to (Z). Diagram (5.2(a)) shows the same boy skating down from position (Y) by using another ramp. Diagram (5.2(b)) shows the velocity-time graph of the boy from (Y) to (Z). … Read more

Kinetic EnergyKinetic energy is the energy of motion. Equation of Kinetic Energy ExampleDetermine the kinetic energy of a 2000-kg bus that is moving with a speed of 35.0 m/s. Answer: Kinetic Energy,

Gravitational Field A gravitational field as a region in which an object experiences a force due to gravitational attraction. Gravitational Field Strength The gravitational field strength at a point in the gravitational field is the gravitational force acting on a mass of 1 kg placed at that point. The unit of gravitational field strength is … Read more

Arrangement in series: Arrangement in parallel: Extension = x × number of springStiffness decreasesSpring constant = k/number of spring Extension = x ÷ number of springStiffness increasesSpring constant = k × number of spring Factors Affecting the Stiffness of Spring Stiffer Less stiff Material type of spring(A steel spring is stiffer than a copper spring) … Read more

Hooke’s Law Hooke’s Law states that if a spring is not stretched beyond its elastic limit, the force that acts on it is directly proportional to the extension of the spring. Elastic Limit The elastic limit of spring is defined as the maximum force that can be applied to a spring such that the spring … Read more

Elasticity Elasticity is the ability of a substance to recover its original shape and size after distortion. Forces Between AtomsThe intermolecular forces consist of an attractive force and a repulsive force. At the equilibrium distance, d, the attractive force equal to the repulsive force. If the 2 atoms are brought closer, the repulsive force will … Read more

Efficiency The efficiency of a device is defined as the percentage of the energy input that is transformed into useful energy. Example:In the example above, the input power is 100J/s, the desire output power (useful energy) is only 75J/s, the remaining power is lost as undisire output. Therefore, the efficiency of this machine is Efficiency= … Read more