A team of students builds a lever as a science project. They expend 10,300 Joules of energy to lift some bricks with the lever. If 6,283 Joules of energy are applied to the bricks, what is the lever’s efficiency?
The efficiency of a lever is determined by dividing the output energy by the input energy and multiplying by 100% to get a percentage. Therefore, the efficiency of the lever in this case can be calculated as follows:
Efficiency = (Output Energy / Input Energy) x 100%
The output energy is the energy used to lift the bricks, which is given as 6,283 Joules in the problem. The input energy is the energy expended by the team to lift the bricks, which is given as 10,300 Joules in the problem. Therefore:
Efficiency = (6,283 / 10,300) x 100%
Efficiency = 0.61 x 100%
Efficiency = 61%
Therefore, the efficiency of the lever is 61%.
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The sentence that best describes how a self-directed learner might investigate gravity is:
"She would think of a way to test the effect of gravity, develop a plan, and carry out the investigation."
A self-directed learner takes responsibility for their own learning and is proactive in seeking out information and solving problems. Therefore, such a learner will not rely solely on online sources or instructions from a teacher but will develop their own ideas and methods for investigating a topic. In this case, a self-directed learner would explore various ways to test the effects of gravity and develop a plan for carrying out an investigation based on their own interests and goals.
The correct answer is:
15.54 meters per second
Here is the step-by-step solution:
The force of air resistance acting on an object is given by the formula:
F = 0.5 * ρ * v^2 * Cd * A
where:
- F is the force of air resistance
- ρ is the density of air
- v is the velocity of the object relative to the air
- Cd is the coefficient of drag
- A is the cross-sectional area of the object
At terminal velocity, the force of air resistance is equal in magnitude but opposite in direction to the force of gravity, so:
F = m * g
where:
- m is the mass of the object
- g is the acceleration due to gravity (9.81 m/s^2)
Setting these two equations equal to each other, we get:
m * g = 0.5 * ρ * v^2 * Cd * A
Solving for v, we get:
v = √(2 * m * g / (ρ * Cd * A))
Plugging in the given values, we get:
v = √(2 * 0.065 kg * 9.81 m/s^2 / (1.1 kg/m^3 * 0.6 * 0.008 m^2))
v ≈ 15.54 m/s
Therefore, the data recorder's velocity is approximately 15.54 meters per second when it hits the ground.
When thermal energy is applied to water, its molecules gain kinetic energy.
Thermal energy is a form of energy that is associated with the motion of particles in a substance. When thermal energy is added to water, the heat energy causes the molecules of water to move and vibrate more rapidly, and this increase in motion and vibration corresponds to an increase in kinetic energy.
Therefore, the correct choice is:
Its molecules gain kinetic energy.
which sentence best describes how a self-directed learner might investigate gravity?
She would only repeat a gravity experiment that she researched online.
She would only follow her teacher's instructions for testing the effects of gravity.
She would only join a team of students that is carrying out of gravity experiment.
She would think of a way to test the effect of gravity, develop a plan, and carry out the investigation.
HELPPP!!!
A team of students is testing for a toy rocket. They want the rocket to land safely so that they can refuel it and use it again. How can they design a parachute that will make the rocket land at a slower velocity?
They can make a parachute hat deploys sooner.
They can make a parachute with less mass.
They can make a parachute with more mass.
They can make a parachute with greater surface area.
They can make a parachute with greater surface area.
The primary function of a parachute is to create air resistance, which slows down the velocity of the object to which it is attached. The amount of air resistance depends on factors such as the size, shape, and mass of the parachute. In this case, the students want to slow down the velocity of the toy rocket so that it lands safely. Therefore, they should design a parachute with a greater surface area, which will increase the amount of air resistance and slow down the descent speed of the rocket.
A weather balloon drops a data recorder from 3,000 meters. The recorder has a mass of 65 grams and presents an area of 0.008 square meter. Air density is 1.1 kilograms per cubic meter, and the coefficient of drag on the recorder is 0.6. What is the data recorder's
156.91 meters per second
16.33 meters per second
15.54 meters per second
4.96 meters per second