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3 years ago

a red kangaroo can hop at speeds of 65 km/hr. how much time will it take the kangaroo to hop 0.25 km at that speed?

Physics

1 answer:

daser333 [38]3 years ago

3 0

Time = (distance) / (speed)

Time = (0.25 km) / (65 km/hr)

Time = 0.00385 hour

(That's 13.85 seconds.)

Better way:

Distance = 0.25 km

Distance = 250 meters

Speed = (65 km/hr) x (1000 m/km) x (1 hr/3600 sec)

Speed = 18.06 m/sec

Time = (250 m) / (18.06 m/s)

Time = 13.85 seconds

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I attach a 4.1 kg block to a spring that obeys Hooke's law and supply 3.8 J of energy to stretch the spring. I release the block

borishaifa [10]

Answer:

The amplitude of the oscillation is 2.82 cm

Explanation:

Given;

mass of attached block, m = 4.1 kg

energy of the stretched spring, E = 3.8 J

period of oscillation, T = 0.13 s

First, determine the spring constant, k;

$T = 2\pi \sqrt{\frac{m}{k} }$

where;

T is the period oscillation

m is mass of the spring

k is the spring constant

$T = 2\pi \sqrt{\frac{m}{k} } \\\\k = \frac{m*4\pi ^2}{T^2} \\\\k = \frac{4.1*4*(3.142^2)}{(0.13^2)} \\\\k = 9580.088 \ N/m\\\\$

Now, determine the amplitude of oscillation, A;

$E = \frac{1}{2} kA^2$

where;

E is the energy of the spring

k is the spring constant

A is the amplitude of the oscillation

$E = \frac{1}{2} kA^2\\\\2E = kA^2\\\\A^2 = \frac{2E}{k} \\\\A = \sqrt{\frac{2E}{k} } \\\\A = \sqrt{\frac{2*3.8}{9580.088} }\\\\A = 0.0282 \ m\\\\A = 2.82 \ cm$

Therefore, the amplitude of the oscillation is 2.82 cm

8 0

3 years ago

¡¡¡AYUDA CON ESTOS EJERCICIOS DE FÍSICA!!!

asambeis [7]

Answer:

(a) 8 V, (b) 144000 V, (c) 2 x 10^(-8) C

Explanation:

(a) charge, q = 5 μC , Work, W = 40 x 10-^(-6) J

The electric potential is given by

W = q V

$40\times10^{-6}=5 \times10^{-6}\times V\\\\V = 8 V$

(b)

charge, q = 8 x 10^(-6) C, distance, r = 50 cm = 0.5 m

Let the potential is V.

$V =\frac{k q}{r}\\\\V =\frac{9\times 10^{9}\times 8\times 10^{-6}}{0.5}\\\\V =144000 V$

(c)

Work, W = 8 x 10^(-5) J, Potential difference, V = 4000 V

Let the charge is q.

W= q V

$8\times10^{-5}= q\times 4000\\\\q =2\times 10^{-8} C$

3 0

3 years ago

The weight of the windsurfer is 700 newtons. Calculate the moment exerted by the windsurfer on the sailboat

borishaifa [10]

Hey, I think someone should help u cause I’m stuck too

Hope this helps !

6 0

2 years ago

State how you agree or disagree with the following statement. A good circuit cannot have internal resistance.

Rashid [163]

Answer: I do

Explanation:

Resistance opposes current thereby reducing the amount of current that flows through a circuit. In other words, it leads to a loss of electrical energy.

Ideally speaking, a good circuit should have no internal resistance as this would lead to more energy having to be supplied to overcome that resistance. External resistance however, is not a bad thing. For instance, oxygen being removed from lightbulbs.

7 0

3 years ago

A person is lifting a heavy box using a lever. What is the purpose of the lever in this situation?

ruslelena [56]

Answer:

to reduce the force needed to lift the box and change the direction of the force

Explanation:

1. "A lever consists of a rigid bar that is able to pivot at one point. This point of rotation is known as the fulcrum. A force is applied at some point away from the fulcrum (typically called the effort)."

By this definition, we know that force is needed to lift an object using a lever.

2. "When the input and output forces are on opposite sides of the fulcrum, the lever changes the direction of the applied force. This occurs only with first-class levers. When both the input and output forces are on the same side of the fulcrum, the direction of the applied force does not change"

For example, on a sew saw, if a force is applied on one end, you on the other side/end would go up, meaning a change in direction.

3. Lastly, we know a lever is typically used to reduce work, in other words, the force needed to move something.

Basically, if we were to put a lever into an equation:

reduced force + change in direction = lever

(the expection) unless load and force are on the same side, there will be no change in direction.

For example, if you and your friend sit on the same side of a sew saw, the sew saw would not go up or down, meaning no change in direction.

So if not stated otherwise you can assume the load and force are on opposite sides. The purpose of a lever in that situation would be to reduce the force needed to lift the box and change the direction of the force.

*While reading my explanation, it may be helpful to look up a diagram containing a lever, with a load, fulcrum, and applied force.

6 0

2 years ago