2.0 meters The skateboarder has 2 forces acting upon him to slow him down. The forces are friction, and climbing against the gravitational acceleration. So let's calculate the magnitude of these forces to see how fast he's decelerated. The coefficient of kinetic friction is a multiplier to use against the normal force of the object. We can calculate the normal force by multiplying the mass of the object by the local gravitational acceleration and the cosine of the angle. So Df = 60 kg * 9.8 m/s^2 * cos(20°) * 0.30 Df = 60 kg * 9.8 m/s^2 * 0.939692621 * 0.30 Df = 60 kg * 9.8 m/s^2 * 0.939692621 * 0.30 Df = 165.7617783 kg*m/s^2 Df = 165.7617783 N
The second amount of force is that caused by gravitational acceleration while climbing. That is determine by the amount of height gained for every meter along the slope. We can calculate that using the sine of the angle. So
Dg = 60 kg * 9.8 m/s^2 * sin(20°)
Dg = 60 kg * 9.8 m/s^2 * 0.342020143
Dg = 201.1078443 kg*m/s^2
Dg = 201.1078443 N
So the amount of force decelerating the skateboarder is:
F = Df + Dg
F = 165.7617783 N + 201.1078443 N
F = 366.8696226 N
Now let's determine how much kinetic energy needs to be dissipated. The equation is
E = 0.5 MV^2
So we'll substitute the known values and calculate
E = 0.5 MV^2
E = 0.5* 60 kg * (5 m/s)^2
E = 0.5* 60 kg * 25 m^2/s^2
E = 750 kg*m^2/s^2
E = 750 J
Now let's divide the energy by the force.
750 kg*m^2/s^2 / 366.8696226 kg*m/s^2 = 2.04432298 m
Rounding to 2 significant figures gives a distance of 2.0 meters.
Work done is given by the change in kinetic energy of an object
- The kinetic energy of the shovel, the shrub, and in Robert's movement were changed, therefore, work is done in the given processes,
Reason:
Work is done when the total energy of object is affected by the application of force on the object over a distance
Therefore;
- In option <em>A</em>, pushing the shovel into ground (to dig out the dirt) the requires the application of a force (push) over a distance, (into and out of the ground) therefore work is done
- In option <em>B</em>, picking the shrub up gives it gravitational potential energy, therefore, work is done
- In option <em>C</em>, carrying the shrub to the hole does visible work
- In option <em>D</em>, holding the shrub while lowering it into the hole does work by preventing the shrub from falling randomly
Therefore, <u>work is done in the given processes</u>
Learn more about work-energy theorem here:
brainly.com/question/10063455
Answer:
The displacements are not equal. While their direction is the same, their length (i.e., distance or magnitude) is not. A is longer than B.
Explanation:
correct on e2020- sample respnse
Answer:
In the present study, the startle blink reflex is used as a measure of emotion regulation to effective picture stimuli. Based on the aphasic theory of emotion, it is hypothesized that the startle response will be largest in magnitude in the presence of negative emotional stimuli (Varanasi, Spence, & Lang, 1988).
Answer:
The scientific method is the process by which scientists gain confidence in theories by failing to prove them wrong.
Explanation:
Scientific method is a step by step process of creating and carrying out experiments. These processes to be performed are derived from logical and rational application of knowledge concerning a particular subject matter. Through these processes, scientists reach a conclusion about the world, these makes them confident in their findings.
The steps involved in scientific method include:
Observation: it is the first step. It enables you organise in your mind how you want the experiment to.
HYPOTHESIS is the result you imagine you'll find.
PREDICTION is how you think about the scientific idea- It solely relies on the hypothesis made.
EXPERIMENT is used to test your hypothesis. It is the tool designed to check if your idea is right or wrong.
CONCLUSION is the final step. It is the result gotten from the experiment. It can approve the hypothesis or reject the hypothesis.
A theory is formed when hypothesis has been tested to be true by many scientists. Hence scientists gain confidence in theories when the scientific method is approved.
A scientific theory is a well-approved explanation of an aspect of the natural world. The approval is based on thoroughly confirmed hypothesis and experiments carried out by many scientists.
