29/01/2023
Are you preparing for MDCAT/ETEA exams and looking for ways to improve your physics skills? Look no further! In this post, we'll be covering some top physics tricks and mathematical problem-solving techniques that every MDCAT aspirant should know. From solving complex MCQs to understanding fundamental physics concepts, this post will provide you with the tools you need to ace your exams. So, whether you're a beginner or an experienced student, read on to sharpen your physics skills!
*Steps:*
1: Read the question carefully and understand what is being asked.
2: Identify the formula that can be used to solve the problem and make sure to understand the physical concepts involved.
3: Substitute the given values into the formula and simplify the expression as much as possible..
*Here's an example to illustrate this process:*
*Question:* What is the force acting on a 2 kg object moving at a velocity of 5 m/s when it is subjected to a net force of 10 N?
1: Read and understand the question: We are asked to find the force acting on an object with a mass of 2 kg and velocity of 5 m/s when subjected to a net force of 10 N.
2: Identify the formula and concepts: We can use the formula F = ma, where F is the force, m is the mass, and a is the acceleration.
3: Substitute and simplify: We know that the acceleration can be calculated as a = F/m, so substituting the given values, we get a = 10 N / 2 kg = 5 m/s^2. We can then find the force acting on the object by multiplying the mass by the acceleration, F = ma = 2 kg * 5 m/s^2 = 10 N.
*Question:* A ball is thrown vertically upwards with a velocity of 20 m/s. What is its maximum height?
1: Read and understand the question: We are asked to find the maximum height of a ball thrown vertically upwards with a velocity of 20 m/s.
2: Identify the formula and concepts: We can use the kinematic equation, h = vi*t + 1/2 * a * t^2, where h is the height, vi is the initial velocity, t is the time, and a is the acceleration due to gravity (g = 9.8 m/s^2).
3: Substitute and simplify: We know that the initial velocity is 20 m/s and the acceleration is 9.8 m/s^2. To find the time, we can use the equation vf = vi + at, where vf is the final velocity (0 m/s for a ball thrown vertically upwards). Solving for t, we get t = vf - vi / a = 0 - 20 / 9.8 = -2.04 s. Substituting this value of t back into the first equation, we get h = 20 * -2.04 + 1/2 * 9.8 * (-2.04)^2 = 41.67 m.
*Question:* A projectile is launched with a velocity of 30 m/s at an angle of 60° above the horizontal. Determine the maximum height and range of the projectile.
1: Read and understand the question: We are asked to determine the maximum height and range of a projectile launched with a velocity of 30 m/s at an angle of 60° above the horizontal.
2: Identify the formula and concepts: We can use the kinematic equations, x = vi * t * cos(θ), y = vi * t * sin(θ) - 1/2 * g * t^2, where x and y are the horizontal and vertical displacement, respectively, vi is the initial velocity, t is the time, θ is the launch angle, and g is the acceleration due to gravity (9.8 m/s^2).
3: Substitute and simplify: We know that the initial velocity is 30 m/s, the launch angle is 60°, and the acceleration is 9.8 m/s^2. We can use the horizontal displacement equation to find the time, x = vi * t * cos(θ), and substitute this value of t into the vertical displacement equation to find the maximum height, y = vi * t * sin(θ) - 1/2 * g * t^2.
4: Solve for the maximum height: To find the maximum height, we need to find the value of t at the peak of the trajectory. This occurs when the vertical velocity is 0 m/s. Using the equation vf = vi + at, where vf is the final velocity (0 m/s), we get t = vf - vi / a = 0 - vi / g = - vi / g = -30 / 9.8 = -3.06 s. Substituting this value of t into the vertical displacement equation, we get y = 30 * -3.06 * sin(60) - 1/2 * 9.8 * (-3.06)^2 = 52.76 m.
5: Solve for the range: To find the range, we need to find the total horizontal displacement, x = vi * t * cos(θ). We can use the value of t found in step 4, t = -3.06 s. Substituting the values into the equation, we get x = 30 * -3.06 * cos(60) = 52.76 m.
*Question:* A body of mass 5 kg is moving with a velocity of 4 m/s, calculate its kinetic energy.
1: Read and understand the question: We are asked to calculate the kinetic energy of a body of mass 5 kg that is moving with a velocity of 4 m/s.
2: Identify the formula and concepts: We can use the formula for kinetic energy, KE = 1/2 * m * v^2, where m is the mass of the body and v is its velocity.
3: Substitute and simplify: Substituting the given values of m = 5 kg and v = 4 m/s into the formula for kinetic energy, we get KE = 1/2 * 5 * 4^2 = 1/2 * 5 * 16 = 40 J.
*Question:* A car of mass 800 kg is moving with a velocity of 30 m/s. It collides with a wall and comes to rest in a distance of 2 m. Determine the force exerted by the wall on the car during the collision.
1: Read and understand the question: We are asked to determine the force exerted by the wall on the car during a collision, where the car has a mass of 800 kg and was moving with a velocity of 30 m/s, and comes to rest in a distance of 2 m.
2: Identify the formula and concepts: We can use the work-energy theorem, ΔKE = work done on an object, to determine the force exerted by the wall on the car during the collision. The force can be calculated using the equation F = Δp / Δt, where Δp is the change in momentum and Δt is the change in time.
3: Calculate the change in kinetic energy: The change in kinetic energy is equal to the negative work done by the force exerted by the wall on the car during the collision. Using the equation ΔKE = 1/2 * m * v^2 - 1/2 * m * 0^2 = 1/2 * 800 * 30^2 = 54000 J, where m is the mass of the car, v is its initial velocity, and 0 is its final velocity (when it comes to rest).
4: Determine the change in momentum: The change in momentum can be calculated using the equation Δp = m * Δv = m * (vf - vi), where Δv is the change in velocity, and vi and vf are the initial and final velocity, respectively. Since the car comes to rest in a distance of 2 m, we can use the equation Δx = vi * t + 1/2 * a * t^2 to find the change in velocity, Δv = 2 * a = 2 * F / m, where a is the acceleration and F is the force exerted by the wall on the car.
5: Calculate the force exerted by the wall: Substituting the values into the equation F = Δp / Δt, where Δp = m * Δv, and Δt is the change in time (which is very small), we can calculate the force exerted by the wall on the car. The value of F can be quite large, as the change in time is very small.
