Solve for the linear/tangential speed:
<em>a</em> = <em>v</em>²/<em>r</em>
where <em>a</em> = centripetal acceleration, <em>v</em> = speed, and <em>r</em> = radius.
4.7 m/s² = <em>v</em>²/(0.3 m)
<em>v</em>² = (0.3 m) (4.7 m/s²)
<em>v</em> ≈ 3.96 m/s
For every time the record completes one revolution, a fixed point on the edge of the record travels a distance equal to its circumference, which is 2<em>π</em> (0.3 m) ≈ 1.88 m. So if 1 rev ≈ 1.88 m, then the angular speed of the record is
(3.96 m/s) (1/1.88 rev/m) ≈ 7.46 rev/s
Take the reciprocal of this to get the period:
1 / (7.46 rev/s) ≈ 0.134 s/rev
So it takes the record about 0.134 seconds to complete one revolution.
Answer:
Explanation:
The height to which a ball will bounce depends on the height from which it is dropped, what the ball is made out of (and if it is inflated, what the pressure is), and what the surface it bounces from is made out of. The radius of the ball doesn't really matter, if you are measuring the height of the ball from the bottom of the ball to the ground.
A ball's gravitational potential energy is proportional to its height. At the bottom, just before the bounce, this energy is now all in the form of kinetic energy. After the bounce, the ball and the ground or floor have absorbed some of that energy and have become warmer and have made a noise. This energy lost in the bounce is a more or less constant fraction of the energy of the ball before the bounce. As the ball goes back up, kinetic energy (now a bit less) gets traded back for gravitational potential energy, and it will rise back to a height that is the original height times (1-fraction of energy lost). We'll call this number f. For a superball, f may be around 90% (0.9) or perhaps even bigger. For a steel ball on a thick steel plate, f is >0.95. For a properly inflated basketball, f is about 0.75. For a squash ball, f might be less than 0.5 or 0.25 - squash balls are not very bouncy. The steel ball on an unvarnished pine wood floor may not bounce at all, but rather make a dent, and so what the floor is made out of makes quite a lot of difference.
<span>When water freezes to form ice, its volume expands. However, we know from conservation of mass that the mass of the ice is the same as the mass of the water. Since density is defined fundamentally as mass / volume, and we have an expanding volume at a constant mass, the denominator of the equation grows, and thus the density of ice is lower than that of liquid water.</span>
Answer:
Explanation:
kinetic energy=1/2*mass*velocity^2
=1/2*14kg*10^2
=7*100
=700 joule
Answer:
Front weels
Explanation:
Because they are the one which select the direction of the car.
