Kathy is changing the tire of her car on a steep hill 20m high. She trips and drops the 10kg spare tire which rolls down the hill. What is the speed of the tire at the top of the next hill if the height of the hill is 5m high?

The Ideal Mechanical Advantage (IMA) of the ramp used to move the stereo is 2. This is calculated by dividing the length of the ramp (3 meters) by its height (1.5 meters).

The question is asking for the Ideal Mechanical Advantage (IMA) of the ramp, also known as an inclined plane, used in moving the stereo. The IMA for an inclined plane, or ramp, can be calculated using the formula IMA = length of slope / height of slope. In this scenario, the length of the ramp is 3 meters and the height is 1.5 meters. Plugging these values into the formula, the IMA is calculated as 3 / 1.5 = 2. This means that the ramp multiplies the force applied to the stereo by two, making the task of loading the stereo easier.

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Answer:

C. protostar

Explanation:

Due to the effect of gravity the hydrogen atoms are pulled together from the nebula. At this stage the star is not hot enough to start the nuclear fission. At this stage a star is called protostar. Eventually it will grow in size by attracting more hydrogen. When the temperature at the core is increased enough due to the gravitational pressure at the core of the star, then nuclear fission will start

The frictionless ramp A will give the ball the greatest speed at the bottom of the ramp.

Speed is defined as the rate of change of the distance or the height attained. it is a time-based quantity. it is denoted by u for the initial speed while u for the final speed. its si unit is m/sec.

The potential energy is due to the virtue of the position and the height. The unit for the potential energy is the joule. Ball has the most potential energy due to her position at C.

The potential energy is mainly dependent upon the height of the object.

Potential energy = mgh

The potential energy gets converted into kinetic energy at the bottom. If the ramp is frictionless the potential energy completely gets converted into kinetic energy.

The kinetic energy results in the motion of the body.

Hence frictionless ramp A will give the ball the greatest speed at the bottom of the ramp.

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The efficiency of the machine is  54.76%.

The efficiency of a machine refers to the amount of useful work that is done by the machine. Efficiency is usually expressed as a percentage.

From the question;

Work output= 230 J

Work input=  420 J

We know that efficiency = Work output/work input × 100/1

efficiency =230 J/420 J × 100/1

efficiency = 54.76%

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Answer: The answer to this question is Unbalanced force.

Explanation: There are two types of forces:

1. Balanced force: When two forces equal in their magnitude act opposite to each other are known as balanced force. The net force is equal to 0.

2. Unbalanced force: When two forces acting opposite to each other are not equal in magnitude results in the unbalanced force. The net force of this is not equal to 0. Direction of force is in the direction of net force.

Now, according to Newton's first law of motion, which says that force is the product of the object's mass and acceleration. The force should have some value and hence it cannot be equal to zero. therefore the force must be Unbalanced force.

According to Newton's second law of motion, a net external force causes a body to accelerate, with the acceleration being directly proportional to the force and inversely proportional to its mass.

According to Newton's second law of motion, a force is expected to cause a body to accelerate when it acts upon the body. This law can be summarized by the equation Fnet = ma, where Fnet denotes the net force acting on the body, m stands for mass, and a signifies acceleration. Therefore, the linear acceleration of a rigid body is directly proportional to the net force acting on it and inversely proportional to its mass. It is important to note that the acceleration occurs in the same direction as the net external force. In simple terms, if you apply a net external force to an object, it will accelerate, and the magnitude of this acceleration can be calculated by dividing the net force by the object’s mass.

Answer:

a. its velocity is zero.

Explanation:

At maximum height no activities is going on that is the velocity becomes zero because no movement occurs at that point

Since there is no moveent the velocity is zero.

At an object's maximum height in projectile motion, its velocity is zero but its acceleration due to gravity remains constant. Therefore, the correct statement is option a).

Here is the detailed reasoning:

An object thrown upwards will decelerate due to gravity until its velocity becomes zero at the maximum height. This is the point where its upward motion stops, and it is about to start descending.

The velocity magnitude at maximum height is zero, but its acceleration is still the acceleration due to gravity (g), acting downwards. Therefore, option d. its acceleration is zero, is incorrect.

Terminal velocity refers to the constant speed that a free-falling object eventually reaches, which is not relevant here. So, option b is incorrect.

Even at its maximum height, an object is still under the influence of gravity, meaning it is in free fall, which makes option c incorrect.

Therefore, the correct answer is a. its velocity is zero.    

Answer:

1. B

2. D

Explanation:

1. Radioactive decay occurs when a radioactive particle cannot maintain a high energy state due to its own weight. When a radioactive element (eg. Uranium) undergoes radioactive decay, its product/s (following the previous example, Uranium decays into Thorium) are more stable than its reactants.

The question might remain that after Uranium decays to Thorium, where does the extra mass go? The extra mass is released as an alpha particle, and through this process, a lot of energy is released as gamma radiation.

Hence, the answer is:

During radioactive decay, atoms break down releasing particles or energy.

2. The half-life of an element is referred to as:

The length of time taken for one half of the radioactive atoms in a sample to decay.

Hence, since the question states the definition of a half-life, the answer is D.

The correct answer is (b) 'During radioactive decay, atoms break down, releasing particles or energy.' And, the term for the time it takes for one-half of the radioactive atoms in a sample to decay is (d) 'half-life.'

The true statement about radioactive decay is option (b), 'during radioactive decay, atoms break down, releasing particles or energy.' Radioactive decay is a spontaneous process where an unstable atomic nucleus loses energy by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino with case of Electron Capture, or a gamma ray. The other options do not accurately describe this process.

The term referring to the time it takes for one-half of the radioactive atoms in a sample of a radioactive element to decay is option (d), 'half-life.' Half-life is commonly used in nuclear physics and chemistry, and it provides us with a measure of the time scale on which radioactive decay processes occur.

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The Kinetic energy of the athlete will be 50 times of the mass of the athlete.

We have a athlete who completed a 100m race in 10 seconds.

We to estimate the average kinetic energy of the athlete.

The formula to calculate the kinetic energy of any moving body is -

K.E. = [tex]\frac{1}{2} mv^{2}[/tex]

According to question -

Distance covered by athlete = 100 meters

Time taken by the athlete = 10 seconds

Let's assume the mass of the athlete = M Kg

Consider the formula for the Kinetic energy of the body -

K.E. = [tex]\frac{1}{2} mv^{2}[/tex]

We know that -

v = [tex]\frac{distance}{time} = \frac{x}{t}[/tex]

Substituting the value of velocity in equation of kinetic energy -

K.E =  [tex]\frac{1}{2} m(\frac{x}{t}) ^{2}[/tex]

We can see that the kinetic energy of the athlete is -

K.E. [tex]\alpha\; (\frac{x}{t})^{2}[/tex]

Greater the square of the ratio of x and t, greater will be the kinetic energy.

K.E. = 0.5 x M x 10 x 10

K.E. = 50M

Hence, the Kinetic energy of the athlete will be 50 times of the mass of the athlete.

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The most efficient nuclear fission reactor would require a higher ratio of U-235 to U-238 due to the higher fissionability of U-235.

The most efficient nuclear fission reactor would require a higher ratio of U-235 to U-238.

U-235 is the fissile isotope of uranium and readily undergoes fission, producing a large amount of energy. U-238, on the other hand, is a fertile isotope that can be converted into plutonium-239, which is also highly fissionable. By increasing the ratio of U-235 to U-238, more U-235 will be available for fission reactions, leading to a higher energy output and efficiency.

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The power of the toaster, calculated using the formula P = W/t, is 700 Watts.

The power of an appliance like a toaster can be calculated using the formula for power which is P = W/t, where P is Power, W is work done or energy consumed, and t is time.

Given that the toaster does 21,000 Joules of work or consumes 21,000 joules of energy in 30 seconds, the power would thus be calculated as follows: P= 21,000J / 30 s. This equals 700 Watts. So, the toaster has a power of 700 Watts.

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Answer:

Explanation:

The work is defined as the force needed to move an object a certain distance, if there's no change of position, there's no work.

In this case, the work is defined:

[tex]W=Fd[/tex]

Where [tex]F[/tex] is the weight defined with the following equation

[tex]F=W=mg[/tex]

Now, we'll replace all given values and solve for [tex]m[/tex]:

[tex]W=mgy\\178=m(9.8)(0.5)\\m=\frac{178}{4.9}=36.33 kg[/tex]

Therefore, the mass is 36.33 kilograms.

The energy used by the construction worker running the jackhammer for 1.5 hours, which has a power of 2.4 kilowatts, is calculated as 3.6 kilowatt-hours, which is answer choice A.

The energy used by the construction worker while running the jackhammer can be calculated using the formula for electrical energy, which is:

E = Pt

Where:

Given:

Therefore, substituting the values we get:

E = 2.4 kW * 1.5 h = 3.6 kilowatt-hours

The correct answer is A. 3.6 kilowatt-hours.

In the solid state of matter, the particles are closest together. Thus, the correct option is B.

The state of matter is one of the distinct forms in which the matter can exist in nature. Four states of matter which are observable in the everyday life are solid, liquid, gas, and plasma states.

Solid state of matter is a state in which the particles are packed tightly in space. The constituent particles can be atoms or the solid particles. The intermolecular distances between the solid particles in the lattice are short and hence the forces of attraction between the molecules are strong. Solids are divided into three broad classes which are crystalline, non-crystalline (amorphous), and quasi-crystalline. Crystalline solids have a very high degree of order in a periodic atomic arrangement of molecules.

Therefore, the correct option is B.

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The mass of the window washer who stands on a scaffolding 30 meters above the ground is 78.4 Kg.

Energy of the body due to its position with respect to some other object (say earth) is called potential energy.

Given is a a window washer who stands on a scaffolding 30 meters above the ground.

The amount of work done by the window washer will be stored inside him in the form of potential energy. Therefore, we can write -

mgh = 23520

m x 10 x 30 = 23520

m = 23520/300

m = 78.4 Kg

Therefore, the mass of the window washer who stands on a scaffolding 30 meters above the ground is 78.4 Kg.

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By definition we have to:

[tex] v = \frac{dr}{dt}
[/tex]

Where,

dr / dt: rate of change of the position of an object with respect to time

Therefore, we know that in a position graph with respect to time, both variables are proportional.

The proportionality constant is the speed of the object.

Mathematically, this constant represents the slope of the line.

Answer:

To calculate the velocity of an object, the slope of the position vs. time graph should be calculated.

Correct answer choice is :

D) The density changed.

Explanation:

Density is the number of mass placed in a particular volume. The density of an object can vary if either the mass or volume of the object is modified. Fluids, such as water, have a specific density. If an object is thicker than water, it will sink; if it is less thick than water, it will float. Maximum material rises in volume when it gets hotter. For instance, if an iron rod is ignited, it will get longer and thicker and its density will reduce. This occurs because the mass of the rod stays the equivalent, but its volume rises.

The velocity of a ball at t = 1 second when it was thrown up with an initial velocity of 42 ft/s, we differentiate the height function to get the velocity function and substitute t = 1 to find the velocity to be 10 feet per second.

The velocity of a ball thrown straight up into the air at a specific time (t = 1 second), using the given position function y = 42t - 16t². To find the velocity at t = 1, we differentiate the position function with respect to time to get the velocity function v(t) = dy/dt. After differentiation, we get v(t) = 42 - 32t and then plug in t = 1 to find the velocity at that moment.

After substituting t into the velocity function, we get v(1) = 42 - 32(1) = 10 ft/s. Hence, the velocity of the ball at t = 1 second is 10 feet per second.

The gravitational force (weight) of an 8.00 kg object on Earth is 78.4 N. This is calculated using the formula 'w = mg', with 'g' being the Earth's acceleration due to gravity (9.80 m/s²).

The gravitational force exerted on an object by the Earth (also known as the object's weight) can be calculated using the formula w = mg, where m is the mass of the object and g is the acceleration due to gravity. On Earth, the acceleration due to gravity (g) is approximately 9.80 m/s².

For an object with a mass of 8.00 kg, the gravitational force (weight) would be calculated as follows:

w = mg = (8.00 kg)(9.80 m/s²) = 78.4 N

Thus, the Earth exerts a gravitational force of 78.4 N on an object with a mass of 8.00 kg.

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