Most Repeated MDCAT Physics: Forces and Motion MCQs

Explanation

Complementary angles are angles that add up to 90 degrees (e.g., 30 degrees and 60 degrees). In the context of projectile motion, if you launch a projectile at two complementary angles, their ranges will be the same. This is because: sin(180∘−2θ). This relationship holds true due to the properties of the sine function.

Explanation

A mass accelerates uniformly when the resultant force acting on it is constant but not zero.

Explanation

Conservative forces, such as gravitational, electric, and elastic spring forces, depend only on the initial and final positions of an object, meaning the work done is independent of the path taken. On the other hand, frictional force is a non-conservative force because the work done by friction depends on the path taken. This is because frictional forces convert kinetic energy into thermal energy, which is dissipated and cannot be recovered, making the process path-dependent.

Explanation

When an object covers unequal displacements (changes in position) in equal intervals of time is known as variable velocity. This means that the object's speed or rate of change in position varies over time. It can be due to factors such as acceleration or deceleration, where the object is either speeding up or slowing down during the specified intervals of time.

Explanation

Newton's second law states that the force required to accelerate a body is equal to the product of its mass and acceleration. The acceleration will be smaller for a large mass. As a result, more force is required to accelerate the body. The force is imparted through the rope as the firefighter slides down it. Tension is the force exerted on the rope. The minimum tension at the rope when the fireman slide down us given as, mg - ¾ mg This force equating with the minimum tension at the rope, we get: ma = mg - ¾ mg a = g - ¾ g a = g (1 - ¾) a = g/4 The fireman should slide down with a minimum acceleration of ¼ of the acceleration due to gravity.

Explanation

Average speed= total distance/total timeThe car’s journey can be divided into two equal parts of distance ‘d’. Since both distances are equal,Total distance= 2dTotal time= d/v1 (for first part) and d/v2 (for second part)Average speed= 2d / d(1/v1+1/v2)d cancels out leaving 2 / (v1+v2/v1v2)Which can be written as 2v1v2 / v1+v2That is consistent with option B.

Explanation

Acceleration of free fall acts equally on all masses, this is why both objects despite having different masses have the same speed at any point in time. Statement II is correct because two objects have the same velocity but one having 5 times more mass than the other will have 5 times more momentum than the other object. Statement IV is also correct because inertia depends upon mass since a 10N ball has a higher mass it will have greater inertia. Statement III is wrong because objects have different masses so their kinetic energy can not be the same. Statement I is wrong because objects accelerate irrespective of their masses as mentioned before.

Explanation

1. It is possible that object starts to accelerate when the frictional force becomes greater enough due to objects motion to equalize the forward force, so the object starts moving at a constant speed. 2. Now, if the force is less than product of coefficients of friction and weight of the object may remain at rest. 3. If the force applied is greater than product of coefficient of friction and weight of the object, the object accelerates on the direction of force.

Explanation

A car is travelling with uniform acceleration along a straight road. The road has marker posts every 100 m, d = 100 m Initial speed of the car, u = 10 m/s Final speed of the car, v = 20 m/s Let a is the acceleration of the car. It is equal to the rate of change of velocity per unit time.

Explanation

This is the correct answer. We can use the equation of motion: v^2 = u^2 + 2as, where v is the final velocity (0 m/s at the maximum height), u is the initial velocity (19.6 m/s), a is the acceleration due to gravity (-9.8 m/s^2), and s is the displacement (maximum height). Plugging in these values and solving for s gives us 19.6 m.

Explanation

To find the weight of a person, use the formula W = mg, where W is the weight, m is the mass (60 kg), and g is the acceleration due to gravity (approximated here as 10 m/s2). Thus, the weight is calculated as:W = 60 kg × 10 m/s2 = 600 NTherefore, the correct answer is 600 N. Other options are incorrect as they underestimate the weight given the mass of 60 kg and the gravitational acceleration.

Explanation

As m =0.5kg F = 10N Using; F = ma a = F/m a = 10/0.5 a = 20ms^-2. Hence, option D is correct.

Explanation

The time rate of change of momentum is represented as Δp/Δt which is equal to force 'F'. Hence, option B is correct.

Explanation

In projectile motion, horizontal component of velocity remains constant, so horizontal velocity after 2 sec will remain 19.6m/sec. So, correct option is C.

Explanation

improve the jumping record, the long jumper should jump at an angle of 45°.Here's why:Range of a projectile: The horizontal distance a projectile travels (its range) is maximized when the launch angle is 45 degrees, assuming the launch and landing points are at the same height and air resistance is negligible.Long jump as projectile motion: A long jump can be modeled as projectile motion.

Explanation

The unit of momentum is kg.m/s and the unit of mass is kg, so the unit of Pm would be kg2.m/s. This unit is equivalent to the unit of energy, which is the joule J. Therefore, option b is correct.

Explanation

The correct answer is that the acceleration of one projectile relative to the other is zero. This is because both projectiles are subject to the same gravitational force, which provides them with an identical acceleration of 9.8 m/s2 downwards. Therefore, when considering one projectile in relation to the other, there is no difference in acceleration—hence, it is zero.Other options suggest incorrect scenarios: 9.8 m/s2 as a relative acceleration is incorrect because it doesn't account for the fact that both projectiles experience this equally, effectively canceling out any relative difference.

Explanation

Sound Intensity (SI) is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The units associated with SI is the watt per square metre (W/m2).I = P/A =10-3/1 I = 10-3 Wm-2.

Explanation

Drag is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.You feel the drag force when you move your hand through the water. You might also feel it if you move your hand during a strong wind. The faster you move your hand, the harder it is to move.Drag force FD is propotional to the square of the speed of the objects. Mathematically,FD = 1/2 C p Av2, Drag force is directly proportional to the square of velocity, so as the speed of the body increases drag force increases.

Explanation

a one-dimensional elastic collision between two bodies of equal mass, their velocities are exchanged. This means:The first body's velocity after the collision (v₁') is equal to the second body's velocity before the collision (v₂).The second body's velocity after the collision (v₂') is equal to the first body's velocity before the collision (v₁).Therefore, the correct relationship is:v₁' = v₂ v₂' = v₁So the correct answer from the provided options is v1 = v2, v2' = v1. It seems there's a small typo in the options you provided (it should likely be v1' = v2).

Explanation

Momentum is defined as the product of mass and velocity (p = mv).1. Since mass is a scalar quantity, the momentum vector (p) will always have the same direction as the velocity vector (v).2.

Explanation

The slope of a velocity-time graph gives us acceleration.Here's why:Slope: In a graph, the slope is defined as the change in the vertical axis divided by the change in the horizontal axis (rise over run).Velocity-time graph: In this type of graph, the vertical axis represents velocity (v), and the horizontal axis represents time (t).Therefore, the slope of a velocity-time graph is:Slope = (Change in velocity) / (Change in time) = Δv / ΔtBy definition, the change in velocity over time is acceleration (a):a = Δv / ΔtThus, the slope of a velocity-time graph directly represents acceleration.