Class 7 Foundation Physics Test-01

The SI unit of mass is kilogram (kg). The kilogram is the base unit of mass in the International System of Units (SI) and is defined as the mass of the International Prototype of the Kilogram (IPK), a platinum-iridium cylinder kept at the International Bureau of Weights and Measures (BIPM) in France. It is widely used in scientific and everyday contexts for measuring the amount of matter an object contains.

Acceleration is the rate of change in velocity. It measures how quickly an object's velocity is changing. When an object speeds up, slows down, or changes direction, its velocity is changing, and therefore it is experiencing acceleration. Mass, force, and work are not directly related to the rate of change in velocity, so they are not the correct answer in this context.

Displacement refers to the shortest distance between two points. It is a vector quantity that takes into account both magnitude and direction. Unlike distance, which is a scalar quantity and only considers the total length traveled, displacement considers the change in position from the initial point to the final point. Therefore, displacement is the correct answer for the given question.

Speed is the correct answer because it refers to the distance covered in a unit of time. It is a scalar quantity that only considers the magnitude of the displacement and not the direction. Velocity, on the other hand, is a vector quantity that includes both magnitude and direction. Mass and acceleration are unrelated to the distance covered in unit time.

The SI unit of velocity is meters per second (m/sec). This unit represents the distance traveled in meters divided by the time taken in seconds, indicating the rate at which an object changes its position with respect to time. This unit is commonly used to measure the speed of objects in everyday life and scientific calculations.

The product of mass and velocity is called momentum. Momentum is a vector quantity that describes the motion of an object and is determined by both its mass and velocity. It is calculated by multiplying the mass of an object by its velocity. The greater the mass or velocity of an object, the greater its momentum will be. Therefore, momentum is a measure of how difficult it is to stop or change the motion of an object.

Distance is the correct answer because it refers to the length between two given points. It is a scalar quantity that only considers the magnitude of the displacement, regardless of the direction. Distance is commonly measured in units such as meters or kilometers and is used to quantify the extent of separation or travel between two points.

Mass is the correct answer because it refers to the amount of substance an object contains. It is a measure of the inertia of an object and is typically measured in units such as grams or kilograms. Mass is different from weight, as weight is the force exerted on an object due to gravity and can vary depending on the location. Matter refers to anything that has mass and occupies space, while heat is a form of energy.

Force is an external cause that can change or attempt to change the state of a body. It is a physical quantity that can cause an object to accelerate, decelerate, or change direction. Force is measured in Newtons and can be exerted through various means such as pushing, pulling, or gravity. It is responsible for the motion and interactions of objects in the physical world.

The equation P = m * V represents the relationship between power (P), mass (m), and velocity (V). The correct answer is m because it represents the mass in the equation. The power is directly proportional to the mass, meaning that as the mass increases, the power also increases. Therefore, the correct answer is m.

Vectors are physical quantities that have both magnitude and direction. They are used to represent quantities such as displacement, velocity, and force. Scalars, on the other hand, only have magnitude and do not have a specific direction associated with them. Therefore, the correct answer is vectors.

Velocity is the correct answer because it represents the displacement covered in a unit of time. It is a vector quantity that includes both magnitude and direction. Speed, on the other hand, represents the magnitude of displacement covered in a unit of time but does not consider direction. Mass is a completely unrelated concept and is not related to displacement or time. Therefore, velocity is the most appropriate term to describe the displacement covered in unit time.

The momentum of an object is defined as the product of its mass and velocity. In this case, the momentum generated is given as 10 kg.m/s and the mass of the football is given as 2 kg. To find the velocity, we can rearrange the equation for momentum and solve for velocity. Dividing both sides of the equation by the mass, we get velocity = momentum / mass. Plugging in the given values, we have velocity = 10 kg.m/s / 2 kg = 5 m/s. Therefore, the velocity of the football is 5 m/s.

The SI unit of acceleration is meters per second squared (m/s^2). This unit represents the rate at which an object's velocity changes over time. It indicates how much an object's speed increases or decreases in one second. The unit is derived from dividing the change in velocity (m/s) by the time taken (s), resulting in meters per second squared. This unit is commonly used in physics and engineering to measure the acceleration of objects in various scenarios.

The momentum of an object is calculated by multiplying its mass by its velocity. In this question, the mass of the body is given as 20 kg and the velocity is given as 10 m/sec. By multiplying these two values, we get the momentum of the body as 200 kg.m/sec.

The SI unit of momentum is kg.m/sec because momentum is defined as the product of an object's mass and its velocity. The unit for mass is kg and the unit for velocity is m/sec, so when multiplied together, the unit becomes kg.m/sec.

The given equation represents the displacement of an object (s) as a function of time (t) with initial velocity (u) and constant acceleration (a). The missing term in the equation is (at^2/2), which is the contribution of acceleration to the displacement. Therefore, the correct answer is a/2.

After applying the brakes, the car comes to a stop after 5 seconds. The initial velocity of the car is 30 m/s. We can use the equation of motion, v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken. Since the car comes to a stop, the final velocity is 0. Plugging in the values, we get 0 = 30 + a * 5. Solving for a, we find that a = -6 m/s^2. Therefore, the acceleration of the car after applying the brakes is -6 m/s^2.

The acceleration of a car can be calculated using the formula: acceleration = (change in velocity) / (change in time). In this case, the change in velocity is 80 m/sec - 50 m/sec = 30 m/sec. The change in time is 10 seconds. Therefore, the acceleration is 30 m/sec / 10 sec = 3 m/sec^2.

The given equation v^2=u^2+2a is a formula used to calculate the final velocity (v) of an object when its initial velocity (u), acceleration (a), and displacement (s) are known. Therefore, the correct answer is s, representing displacement.