A man stretches a rubber band around a newspaper. What type of

A boy im50kg at rest on a skateboard is pushed by another boy who exerts a force of 200 N on him. If the first boy's

sergey [27]

Answer:

Time, t = 2 seconds

Explanation:

Given the following data;

Mass, m = 50 kg

Initial velocity, u = 0 m/s (since it's starting from rest).

Final velocity, v = 8 m/s

Force, F = 200 N

To find the time, we would use the following formula;

$F = \frac {m(v - u)}{t}$

Making time, t the subject of formula, we have;

$t = \frac {m(v - u)}{F}$

Substituting into the formula, we have;

$t = \frac {50(8 - 0)}{200}$

$t = \frac {50*(8)}{200}$

$t = \frac {400}{200}$

Time, t = 2 seconds

5 0

3 years ago

A small object is attached to the end of a relaxed, horizontal spring whose opposite end is fixed. The spring rests on a frictio

eduard

Answer:4A

Explanation:

Given

Mass is displace x= A units from its mean position x=0'

When it is set to free it will oscillate about its mean position with maximum amplitude A i.e. from x=-A to x=A

One cycle is completed when block returns to its original position

so first block will go equilibrium position x=0 and then to x=-A

from x=-A it again moves back to x=0 and finally back to its starting position x=A

so it travels a distance of A+A+A+A=4A

7 0

3 years ago

For which pair of launch angles will two identical projectiles have equal ranges?. A. 19.24°, 80.54°B. 16.42°, 74.58°C. 60.23°,

AlladinOne [14]

The kinematic equations of motion that apply here arey(t)=votsin(θ)−12gt2andx(t)=votcos(θ)Setting y(t)=0 yields 0=votsin(θ)−12gt2. If we solve for t, we obtain, by factoring,t=2vsin(θ)gSubstitute this into our equation for x(t). This yieldsx(t)=2v2cos(θ)sin(θ)gThis is equal to x=v^2sin(2θ)gHence the angles that have identical projectiles are have the same range via substitution in the last equation is C. 60.23°, 29.77°

4 0

3 years ago

Read 2 more answers

A current I flows down a wire of radius a.

Helga [31]

Answer:

(a) $K = \frac{I}{2\pi a}$

(b) $J = \frac{I}{2\pi as}$

Explanation:

(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

$K = \frac{dI}{dL}$

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

$dL = 2\pi r$

The radius of the wire = a

$dL = 2\pi a$

The surface current density $K = \frac{I}{2\pi a}$

(b) The current density is inversely proportional

$J \alpha s^{-1}$

$J = \frac{k}{s}$ ......(1)

k is the constant of proportionality

$I = \int\limits {J} \, dS$

$I = J \int\limits \, dS$ ........(2)

substituting (1) into (2)

$I = \frac{k}{s} \int\limits\, dS$

$I = k \int\limits^a_0 \frac{1}{s} {s} \, dS$

$I = 2\pi k\int\limits\, dS$

$I = 2\pi ka$

$k = \frac{I}{2\pi a}$

substitute $J = \frac{k}{s}$

$J = \frac{I}{2\pi as}$

7 0

3 years ago

Two separate but nearby coils are mounted along the same axis. A power supply controls the flow of current in the first coil, an

Anit [1.1K]

Answer:

b.only when the current in the first coil changes.

Explanation:

An induced current flow in the second coil only when there is a change in current in the first cool. A steady current will produce no change in flux (due to magnetic effect of a current) by the first coil, and according to Faraday, induced current is only produced when there is a change in flux linkage.

8 0

3 years ago