Ocean waves travel in to the beach at an average velocity of 2.5 m/s
if these waves come in 4 seconds apart, what is the average distance between the wave peaks, considering the formula v=d/t
a) 0.625 m
b) 1.6 m
c) 5.0 m
d) 10.0 m

the wattage of speaker describes the rate at which energy is converted from electrical energy to sound energy. this is the description of which of these?
a) energy
b) power
c) transformation
d) work

a bodybuilder lifts a certain weight up and down. if the body builder does it in less time, which of these statements is most accurate?
a) the body builder uses both the same energy and power.
b) the body builder uses both more energy and more power.
c) the body builder uses the same energy and but more power.
d) the body builder uses the same power and but more energy.

students in a physical education class practiced rope climbing. students gripped a rope that hung from the ceiling and lifted themselves up the rope using only their arms. what must be measured to determine the power output of the climbers?
a) tension on the rope and the final height
b) body mass, final height, and the tension on the rope
c) tension on the rope and the time required to complete the climb
d) body mass, final height, and the time required to complete the climb

1) D)10.0 m

To find the average distance between the wave peaks, we can use the formula:

where in this case:

v = 2.5 m/s is the average velocity

d = ? is the average distance

t = 4 s is the time between two wave peaks

Re-arranging the equation, we find

2) B)Power

This is exactly the definition of power. In fact, power is defined as the ratio between the amount of work done / of energy used, and the time taken for this conversion to occur:

where

W is the amount of work done / of energy used

t is the time taken

3) C)The body builder uses the same energy and but more power.

The energy used by the body builder does not change: in fact, it is only related to the height at which he lift the weight. The work done to lift the weight, of mass m, up to a height of h, is given by

where g is the gravitational acceleration. So, this quantity does not change. Instead, the power changes, because the time the body builder takes to lift the weight up has decreased, and the power depends on the time as we know from the formula:

so, since t has decreased, P has increased.

4) D)body mass, final height, and the time required to complete the climb

The power output is given by:

where:

m is the body mass

g is the gravitational acceleration

h is the final height

t is the time required to complete the climb

Therefore, we see that correct choice is D.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

d. platinum would have the greatest temperature increase because it has the lowest specific heat.