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3 years ago

For the following situations, describe the contact and non-contact forces that are involved.

Physics

2 answers:

Sonja [21]3 years ago

8 0

I think is b not a 100% sure but maybe.

musickatia [10]3 years ago

7 0

Answer:

a. the book is exerting force down on the shelf (due to gravity) while the shelf is exerting force back up at the book.

b. when the soccer player kicks the ball, this is applied force. As the ball soars through the air and lands on the ground, the friction ends the movement of the ball.

c. the compass detects the Earth's natural magnetic feild. This force is non contact, since there is no physical touch between magnetic feilds and the compass.

d. when the child is just sitting on the hill on the sled, this is a contact force. The child is pushing down on the sled and the sled pushes back at the child. When he or she slides off down the hill, this contact force is put to a stop due to friction.

Explanation:

Explanation above for each situation.

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A wire of resistance 5.9 Ω is connected to a battery whose emf ε is 4.0 V and whose internal resistance is 1.2 Ω. In 2.9 min, ho

dexar [7]

Answer:

a) 390J

b) 322J

c) 68J

Explanation:

We need to calculate the power given by the battery. the power is given by:

$P=V*I\\I=\frac{V}{R}\\I=\frac{4}{5.9+1.2}\\I=0.56A\\P=2.24W$

Watts is J/s so:

$E=P*t\\E=2.24\frac{J}{s}*2.9min*(60\frac{s}{min})=390J$

The thermal energy in the wire is given by:

$E_w=P_w*t\\P_w=I^2*R_w=0.56^2*5.9=1.85W\\E_w=1.85\frac{J}{s}*2.9min*(60\frac{s}{min})=322J$

And the the dissipated thermal energy in the battery will be the remainig energy:

$E_b=E-E_w\\E_b=390-322=68J$

4 0

3 years ago

What evidence indicates that a chemical change took place when the iron and sulfur combined to form iron sulfide? A. The element

fgiga [73]

Answer:

Explanation:burn the gas

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3 years ago

Read 2 more answers

A particle with negative charge q and mass m = 2.65×10−15 kg is traveling through a region containing a uniform magnetic field B

Norma-Jean [14]

Answer:

q = 2,95 10-6 C

Explanation:

The magnetic force on a particle is described by the equation

F = q v x B

Where bold indicate vectors

Let's make the vector product

vxB = $\left[\begin{array}{ccc}i&j&k\\-3&4&12\\0&0&-0.13\end{array}\right]$

v x B = 1.20 106 [i ^ (4 0.130) - j ^ (3 0.130)]

vx B = 1.20 106 [0.52 i ^ - 0.39j ^]

As they give us the force module, let's use Pythagoras' theorem,

|v xB | =1.20 10⁶ √( 0.52² + 0.39²)

|v x B| = 1.20 10⁶ 0.65

v xB = 0.78 10⁶

Let's replace and calculate

2.30 = q 0.78 10⁶

q = 2.3 / 0.78 106

q = 2,95 10-6 C

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3 years ago

How long will it take a car to travel a distance of 1km if it has an average speed of 60kph

beks73 [17]

Answer:

1÷60 h

time equals distance upon speed

6 0

3 years ago

Until he was in his seventies, Henri LaMothe excited audiences by belly-flopping from a height of 9 m into 32 cm. of water. Assu

baherus [9]

Answer:

823.46 kgm/s

Explanation:

At 9 m above the water before he jumps, Henri LaMothe has a potential energy change, mgh which equals his kinetic energy 1/2mv² just as he reaches the surface of the water.

So, mgh = 1/2mv²

From here, his velocity just as he reaches the surface of the water is

v = √2gh

h = 9 m and g = 9.8 m/s²

v = √(2 × 9 × 9.8) m/s

v = √176.4 m/s

v₁ = 13.28 m/s

So his velocity just as he reaches the surface of the water is 13.28 m/s.

Now he dives into 32 cm = 0.32 m of water and stops so his final velocity v₂ = 0.

So, if we take the upward direction as positive, his initial momentum at the surface of the water is p₁ = -mv₁. His final momentum is p₂ = mv₂.

His momentum change or impulse, J = p₂ - p₁ = mv₂ - (-mv₁) = mv₂ + mv₁. Since m = Henri LaMothe's mass = 62 kg,

J = (62 × 0 + 62 × 13.28) kgm/s = 0 + 823.46 kgm/s = 823.46 kgm/s

So the magnitude of the impulse J of the water on him is 823.46 kgm/s

6 0

3 years ago