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3 years ago

5

a hollow tennis ball and a lead filled tennis ball are dropped off a tall building. which reaches the ground first, the hollow b

all, or the lead filled ball

2 answers:

Flura [38]3 years ago

5 0

Lead filled. it has a higher mass, therefore gravity pulls on it harder, in turn making it fall faster. think of the saying "the bigger they fall, the harder they fall", in this case its "faster", not "harder."

jolli1 [7]3 years ago

4 0

Lead filled ball because it is less affected by air resistance

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What is the mass of a large dog that weighs 441 newtons

PtichkaEL [24]

Weight, w = mg. g ≈ 9.8 m/s². m = mass in kg. w is weight in N

441 N = m* 9.8

9.8m = 441

m = 441/9.8

m = 45 kg.

Mass of the dog is = 45 kg

5 0

3 years ago

A particle travels along a straight line with a velocity v = (12 - 3t) m/s, where t is in seconds. When t = 1 s, the particle is

Simora [160]

Answer:

(1).The acceleration is -24 m/s²

The total distance is 912 m.

(2). The distance traveled before it stop is 78 m.

Explanation:

Given that,

Velocity = (12-3t^2) m/s

When t = 1 s, the particle is located 10 m to the left of the origin.

We need to calculate the acceleration at t = 4 sec

Using formula of acceleration

$a=\dfrac{dv}{dt}$

Put the value of v

$a=\dfrac{d}{dt}(12-3t^2)$

$a=-6t$

Put the value of t

$a=-6\times4$

$a=-24\ m/s^2$

The displacement from t = 0,t = 10 s, and the distance the particle travels during this time period.

We need to calculate the distance

Using formula of distance

$ds=v\ dt$

$\int_{-10}^{s}=\int_{1}^{t}{v}dt$

Put the value of v

$\int_{-10}^{s}=\int_{1}^{t}{ (12-3t^2)}dt$

$s+10=12t-t^3-11$

$s=12t-t^3-21$

At t = 0,

$s_{t=0}=-21$

At t = 10,

$s_{t=10}=12\times10-10^3-21$

$s_{t=10}=-901$

The displacement is

$\Delta s=-901-(-21)$

$\Delta s=-880\ m$

The distance at t= 2 sec

$s_{t=2}=12\times2-2^3-21$

$s_{t=2}=-5$

The total distance will be,

$s_{T}=(21-5)+(901-5)$

$s_{T}=912\ m$

(2). We need to calculate the distance at 2 sec

Using equation of motion

$s=ut-\dfrac{1}{2}at^2$

Put the value into the formula

$s=27\times 2+\dfrac{1}{2}\times6\times(2)^3$

$s=78\ m$

Hence, (1).The acceleration is -24 m/s²

The total distance is 912 m.

(2). The distance traveled before it stop is 78 m.

3 0

3 years ago

Your friend Nader is standing 400,000 meters away. If you send a message to him using radio waves, how long will it take for him

Citrus2011 [14]

Speed of a radio wave in vacuum/air is 3x10^8 m/s. so, if speed is also distance/time, then time = distance/speed = 400,000/300,000,000 = ????

8 0

3 years ago

How is energy can be changed from one state to another?

snow_lady [41]

Answer:

Explanation:

Heat is probably the easiest energy you can use to change your physical state. The atoms in a liquid have more energy than the atoms in a solid. There is a special temperature for every substance called the melting point.They are changes in bonding energy between the molecules. If heat is coming into a substance during a phase change, then this energy is used to break the bonds between the molecules of the substance. EXAMPLE: Solid ice melting into liquid

5 0

4 years ago

A cylindrical rod with length (1.7 m) and radius (2 cm) is fixed from one end and a mass of (20 kg) is attached to the other fre

belka [17]

Answer:

0.44

Explanation:

Poisson's ratio is:

ν = (3K − E) / 6K

where K is the bulk modulus and E is Young's modulus.

Young's modulus is:

E = FL / (AΔL)

where F is the force, L is the initial length, A is the cross sectional area, and ΔL is the change in length.

E = (20 kg × 9.8 m/s²) (1.7 m) / (π (0.02 m)² × 0.0005 m)

E = 0.530×10⁹ Pa

Bulk modulus is:

K = -ΔP / (ΔV/V)

where ΔP is the change in pressure, ΔV is the change in volume, and V is the initial volume.

K = -(180 atm × 101325 Pa/atm) / (-0.012)

K = 1.52×10⁹ Pa

Therefore, the Poisson's ratio is:

ν = (3(1.52×10⁹ Pa) − 0.530×10⁹ Pa) / 6(1.52×10⁹ Pa)

ν = (3(1.52) − 0.530) / 6(1.52)

ν = 0.442

Rounded to 2 significant figures, the Poisson's ratio is 0.44.

3 0

3 years ago