Force and Motion I

Question 1:What is the meaning of gravitational field strength? Answer:Gravitational field strength, g is the force acting per unit mass caused by gravitational pull or as the ratio of the weight to mass of the object.For objects on the surface of the Earth, gravitational field strength, g is 9.81 N kg–1. Each 1 kg mass … Read more

Question 1:In a car collision test, a car of mass 1 500 kg hits the wall with a speed of 15 m s–1. The car bounces back with a speed of 2.6 m s–1. If the collision time is 0.15 s, calculate the:(i) impulse in the collision(ii) impulsive force acting on the car Answer:(i)$$ \begin{aligned} … Read more

Question 1:A force, F acts on a body of mass 5 kg.(a) If the body accelerates uniformly from 2 m s–1 to 8 m s–1, determine the value of F.(b) If F = 10 N, determine the displacement of the body 6 seconds after the body starts to move from rest. Answer:(a)$$ \begin{aligned} m & … Read more

Question 1: What is meant by momentum and conservation of momentum? Answer:Mementum (p) is product of the mass (m) of an object and its velocity (v).p = mvThe Principle of Conservation of Momentum states that the total momentum before collision is equal to the total momentum after collision if no external force is acting on it. … Read more

Question 1:Explain the concept of inertia. Answer:Inertia is the tendency of an object to remain at rest or, if moving, to continue its motion in a straight line at uniform velocity. Question 2:Brian wishes to pull a table cloth without toppling the things on top of the table cloth. How can Brian do it? Explain … Read more

Question 3:An object thrown vertically upwards reached a maximum height of 5.0 m. Calculate: (a) the velocity of the object when thrown (b) the time taken for the object to reach its maximum height (c) the time required for the object to return to its original level Ignore air resistance. [g = 9.81 m s–2] … Read more

Question 1:What is meant by free fall? Answer:Free fall is motion with acceleration due to gravitational force only. Question 2:A light hollow plastic ball and a solid steel ball of the same size are released from the cliff of a hill. Will both balls reach the foothill at the same time? Explain your answer. Answer:Detailed … Read more

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