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3 years ago

11) A sled is initially given a shove up a frictionless 35º incline. It reaches a maximum height of 2.5

Physics

1 answer:

Andrej [43]3 years ago

5 0

Answer:

7 m/s

Explanation:

To solve this problem you must use the conservation of energy.

$K1 +U1=K2+U2$

That math speak for, initial kinetic energy plus initial potential energy equals final kinetic energy plus final potential energy.

The initial PE (potential energy) is 0 because it hasn't been raised in the air yet. The final KE (kinetic energy) is 0 because it isn't moving. This gives the following:

$KE1= \frac{1}{2}mv^{2}}$

$PE2=mgh$

K1=U2

$\frac{1}{2} mv^{2} =mgh$

Solve for v

$v=\sqrt{2gh}$

Input known values and you get 7 m/s.

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If a 20 g cannonball is shot from a 5 kg cannon with a velocity of 100

balu736 [363]

Strange as it may seem, the statement in the question appears to be TRUE.

-- Before the shot, neither the cannon nor the ball is moving, so their combined momentum is zero.

-- Since momentum is conserved, we know immediately that their combined momentum AFTER the shot also has to be zero.

-- (20g is rather puny for a "cannonball" ... about the same weight as four nickels. But we'll take your word for it and just do the Math and the Physics.)

-- Momentum = (mass) x (velocity)

After the shot, the momentum of the cannonball is

(0.02 kg) x (100 m/s ==> that way)

Momentum of the ball = 2 kg-m/s ==> that way.

-- In order for both of them to add up to zero, the momentum of the cannon must be (2 kg-m/s this way <==) .

Momentum of cannon = (5 kg) x (V m/s this way <==)

2 kg-m/s this way <== = (5 kg) x (V m/s this way <==)

Divide each side by (5 kg):

V m/s = (2/5) m/s this way <==

Speed of recoil of the cannon = -- 0.4 m/s

3 0

3 years ago

The weight of an astronaut plus his space suit on the Moon is only 250 N. (a) How much does the suited astronaut weigh on Earth?

Evgesh-ka [11]

Answer:

a)1500N

b)153.06kg

Explanation:

F = ma

g(moon) = is the acceleration due to gravity on the moon

g(earth) is the acceleration due to gravity on the earth

g(moon) = 1/6g(earth)

g(earth) =6g(moon)

F(gearth) = mg(earth)

= m 6g(moon)

= 6 × 250

= 1500N

b) F(gearth) = mg(earth)

m = F /g

= 1500/9.8

= 153.06kg

3 0

3 years ago

Read 2 more answers

A spinning coil of wire is what moves the cone in a speaker, producing the sound. True/False

Georgia [21]

False, the spinning coil of wire that moves the cone in a speaker does not produces sound.

Explanation:

The wire coil is an electromagnet that is fixed to speaker cone. A normal magnet attached to the back of the speaker cone.When audio is sent in the form of short bursts of electric current to the speaker cone through the wire.

A magnetic field is induced when electric current allowed to pass through the coil. This magnetic field is repelled by the other magnet. This repulsion cause the cone to move forward. In the absence of electric current in the coil, the cone moves backward.

Thus sound waves are produced due to the resulting rarefaction and compression. So it is not the spinning coil of wire but he permanent magnet that produces the sound.

5 0

3 years ago

Read 2 more answers

Which of the following is NOT a good example of a short-term goal?

Molodets [167]

Loose 10 pounds im pretty sure

5 0

3 years ago

Richard Julius once made a model plane that could travel a max speed of 110 m/s. Suppose the plane was held in a circular path b

hjlf

Answer:

85.8 m/s

Explanation:

We know that the length of the circular path, L the plane travels is

L = rθ where r = radius of path and θ = angle covered

Now,its speed , v = dL/dt = drθ/dt = rdθ/dt + θdr/dt

where dθ/dt = ω = angular speed = v'/r where v' = maximum speed of plane and r = radius of circular path

Now, from θ = θ₀ + ωt where θ₀ = 0 rad, ω = angular speed and t = time,

θ = θ₀ + ωt = 0 + ωt = ωt

So, v = rdθ/dt + θdr/dt

v = rω + ωtdr/dt

v = (r + tdr/dt)ω

v = (r + tdr/dt)v'/r

v = v' + tv'/r(dr/dt)

v = v'[1 + t(dr/dt)/r]

Given that v' = 110 m/s, t = 33.0s, r = 120 m and dr/dt = rate at which line is shortened = -0.80 m/s (negative since it is decreasing)

So, v = 110 m/s[1 + 33.0 s(-0.80 m/s)/120 m]

v = 110 m/s[1 + 11.0 s(-0.80 m/s)/40 m]

v = 110 m/s[1 + 11.0 s(-0.02/s)]

v = 110 m/s[1 - 0.22]

v = 110 m/s(0.78)

v = 85.8 m/s

8 0

2 years ago