Force and Motion I

Question 11:Photograph 3 shows a hovercraft which can move on land or on the surface of water swiftly because of the support from a layer of air trapped under the hovercraft . Th e hovercraft of mass of 25 000 kg starts from rest and its engine produces a thrust, F of 22 000 N.(a) … Read more

Question 8:A rubber ball is released from a height, H. The ball drops vertically downwards and upon hitting the floor, bounces back a height, h (h < H). If the velocity of downward motion is negative, sketch the velocity-time graph for the motion of the rubber ball. Answer:For velocity-time graph:Gradient of the graph = accelerationArea … Read more

Question 4:A car of mass 1 200 kg at rest is moved by a force of 150 N. Determine the acceleration of the car and time taken for the car to reach a velocity of 1.5 m s–1. Answer:$$ \begin{aligned} F & =m a \\ 150 & =(1200) a \\ a & =0.125 \mathrm{~m} \mathrm{~s}^{-2} … Read more

Question 1: A car moves from rest with an acceleration of 2.0 m s–2. Calculate:(a) velocity of car after 5.0 s.(b) distance travelled in 5.0 s.(c) distance travelled in the fifth second. Answer:$$ \begin{aligned} u & =0 \mathrm{~ms}^{-1} \\ a & =2.0 \mathrm{~ms}^{-2} \\ t & =5.0 \mathrm{~s} \\ v & =? \end{aligned} $$(a)$$ \begin{aligned} v … Read more

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