Why do hot-air balloons rise?

A roller coaster starts from rest at its highest point and then descends on its (frictionless) track. Its speed is 38 m/s when i

inysia [295]

Explanation:

look !

speed= 38m/s

start from rest= 0

5 0

3 years ago

Assuming a 8 kilogram bowling ball moving at 2 m/s bounces off a spring at the same speed that had before bouncing what is the a

Naya [18.7K]

a) 32 kg m/s

Assuming the spring is initially at rest, the total momentum of the system before the collision is given only by the momentum of the bowling ball:

$p_i = m u = (8 kg)(2 m/s)=16 kg m/s$

The ball bounces off at the same speed had before, but the new velocity has a negative sign (since the direction is opposite to the initial direction). So, the new momentum of the ball is:

$p_{fB}=m v_b =(8 kg)(-2 m/s)=-16 kg m/s$

The final momentum after the collision is the sum of the momenta of the ball and off the spring:

$p_f = p_{fB}+p_{fS}$

where $p_{fS}$ is the momentum of the spring. For the conservation of momentum,

$p_i = p_f\\p_i = p_{fB}+p_{fS}\\p_{fS}=p_i -p_{fB}=16 kg m/s -(-16 kg m/s)=32 kg m/s$

b) -32 kg m/s

The change in momentum of bowling ball is given by the difference between its final momentum and initial momentum:

$\Delta p=p_{fb}-p_i=-16 kg m/s - 16 kg m/s=-32 kg m/s$

c) 64 N

The change in momentum is equal to the product between the average force and the time of the interaction:

$\Delta p=F \Delta t$

Since we know $\Delta t=0.5 s$ , we can find the magnitude of the force:

$F=\frac{\Delta p}{\Delta t}=\frac{-32 kg m/s}{0.5 s}=-64 N$

The negative sign simply means that the direction of the force is opposite to the initial direction of the ball.

d) The force calculated in the previous step (64 N) is larger than the force of 32 N.

5 0

3 years ago

A stone is thrown horizontally from the top of an inclined plane (angle of inclination θ). How would I find the initial speed of

Katen [24]

Answer:

S = V t where S is the horizontal distance traveled

1/2 g t^2 = H where H is the vertical distance traveled

t^2 = 2 H / g

V^2 = S^2 / t^2 = S^2 g / (2 H) combining equations

tan theta = H / S

V^2 = S g / (2 tan theta)

Using S = L cos theta

V^2 = L g cos theta / (2 tan theta)

Giving V in terms of L and theta

7 0

2 years ago

!!!!!!PLEASE HELP ASAP !!!!!!!!!!!!

OLga [1]

Answer: d constint speed

Explanation: im 15 and no the answer

5 0

3 years ago

Ozone in the upper atmosphere absorbs energy in the 210-230 nmnm range of the spectrum. In what region of the electromagnetic sp

kifflom [539]

Answer:

Ultraviolet

Explanation:

The electromagnetic spectrum is divided into a number of parts. One of which is the ultraviolet region. The ultraviolet region is found between the 100 nm - 400 nm band of the electromagnetic spectrum. From the range we just stated now, we can see for certainty that the given range 210 nm - 230 nm lies inside of the 100 nm c 400 nm of the electromagnetic spectrum, that of which is the ultraviolet region.

5 0

3 years ago