Given:
u = 7.00m/s, the initial vertical velocity of the package.
Assume that g = 9.8 m/s².
Neglect air resistance.
All quantities are measured as positive upwards.
The height from which the package is dropped is 155 m above ground.
Let t = the time for the package to hit the ground.
Therefore
(7.00 m/s)*(t s) - (1/2)*(9.8 m/s²)*(t s)² = (- 155 m)
4.9t² - 7t - 155 = 0
or
t² - 1.4286t - 31.6327 0
Solve with the quadratic formula.
t = (1/2)*[1.4286 +/- √(2.0409 + 126.5308)]
= 6.384 s or - 4.955 s
Reject negative time.
Answer: 6.384 s
The addition of antifreeze to
water in a car radiator causes the freezing point of the mixture to increase. The
answer is letter A. It protects the car radiator from freezing due to cold
temperatures. It is added below the freezing point of water to prevent it from
solidifying.
Answer:
The diameter of the hole increases
Explanation:
Metals expand and contract with temperature. Whenever metal is heated, it usually expands in relation to its thermal expansivity. This expansion leads to a slight increase in surface area.
Once the surface area of the metal changes, this means that the dimensions of the whole metal surface changed. As a result, the diameter of the hole drilled in the metal plate will change also. In our case, the diameter of the hole will increase.
<span>So we want to know why the does a bouncing ball rise to a lower height with each bounce. So lets say the ball is first on some height h. There it has potential energy Ep=m*g*h. Then as the ball starts falling to the ground the energy converts to kinetic energy Ek=(1/2)*m*v^2. When the ball falls to the ground, the kinetic energy transforms to elastic energy because the ball deforms as it hits the ground and some small quantity of heat. The heat goes to the air and to the ground so it gets removed from the system. So there is less energy in the system to be converted back to kinetic energy as the ball starts to rise in height again. Thats why the ball is not able to get bact to the same height as it started from. </span>
Answer:
The acceleration is a = 2.75 [m/s^2]
Explanation:
In order to solve this problem we must use kinematics equations.
where:
Vf = final velocity = 13 [m/s]
Vi = initial velocity = 2 [m/s]
a = acceleration [m/s^2]
t = time = 4 [s]
Now replacing:
13 = 2 + (4*a)
(13 - 2) = 4*a
a = 2.75 [m/s^2]