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xxMikexx [17]
3 years ago
7

A person walks 4.0 kilometers north, then 4.0 kilometers west. His displacement is closest to

Physics
1 answer:
larisa86 [58]3 years ago
7 0
Use the Pythagoras for the magnitude and the tan^-1 x = -1 for the angle

displacement = 4^2 + 4^2 = 32 = 4 sqrt(2) =  5.65 km

angle is 135 degrees.

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On a safety test course, a 1000 kg car heading north at 5 m/s collides head-on with an 800 kg car heading south at 4 m/s. At the
Luden [163]

Answer:

The speed is 3.5\frac{m}{s} and the direction is heading north.

Explanation:

In collisions the force exerted by the objects that collide is higher enough than the external forces that we can neglect that external forces, with that assumption we can use the conservation fo momentum law that states, final total momentum (pf) is equal initial total momentum (pi) if there’re not external forces or they are small enough to be neglected. Mathematically:

p_f=p_i

The total momentum is the sum of the momentum of each of the bodies we're dealing, in our case the moment of each car, then:

p_{nf}+p_{sf}=p_{ni}+p_{si}

with pn the momentum of the 1000kg car heading north and ps the 800kg car heading south. Momentum is defined as mass times velocity, then:

m_nv_{nf}+m_sv_{sf}=m_nv_{ni}+m_sv_{si} (1)

It's important to note that when we talk about momentum and velocity direction matters, so we're are going to choose a system of reference where quantities pointing north are positive and pointing south are negative. So, the initial velocity of 1000 kg car is vni=5 m/s, initial velocity of 800 kg car is vsi=-4 m/s and the final velocity of 1000 kg car is vnf=-1 m/s. Now we can solve (1) for vsf and use the values we already have:

v_{sf}=\frac{m_nv_{ni}+m_sv_{si}-m_nv_{nf}}{m_s}=\frac{(1000)(5)+(800)(-4)-(1000)(-1)}{800}

v_{sf}=3.5\frac{m}{s}

Because the sign is positive the direction is to heading north.

7 0
3 years ago
Express the number in scientific notation: 4/100
ankoles [38]

Answer:

4*10^-2

Explanation:

for the scientific notation the first number must be between 1 and 10, so in this case it is 4. 4/100 is also equal to 0.04, and if we could the number of places before 4, there are two, therefore 4 times 10 to the power of -2

5 0
3 years ago
Is pulling a dog a contact force or a non contact force
horrorfan [7]
A contact force since you are making physical contact with the dog

Mark my brainliest please
6 0
3 years ago
The gravitational force between two objects depends on the masses and what factor between them?
Charra [1.4K]
It depends on mass and distance.  
8 0
3 years ago
A dad pushes tangentially on a small hand-driven merry-go-round and is able to accelerate it from rest to a frequency of 18 rpm,
puteri [66]

Answer:

F = 176.175 N

Explanation:

given,  

radius of merry - go - round = 2.7 m

mass of the disk = 800 kg  

speed of the merry- go-round = 18 rpm  

                                                 = 18 \dfrac{2\pi }{60}

                                                 = 1.88 rad/s

time = 13 s

mass of two children = 25 kg  

ω = ω₀ + α t

1.88 = 0 + α(13)

α = 0.145 rad/s²

we know

τ = I α

so,

I = \dfrac{1}{2}MR^2+ 2 MR^2  

I = \dfrac{1}{2}\times 800 \times 2.7^2+ 2\times 25\times 2.7^2

I = 3280.5 kg.m^2  

τ = I α

τ = 3280.5 x 0.145

τ = 475.67 N m

τ = F x r

475.67 = F x 2.7

F = 176.175 N

4 0
3 years ago
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