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olganol [36]
3 years ago
6

Select the correct answer.

Physics
2 answers:
FinnZ [79.3K]3 years ago
8 0
2 hours is the answer because you do 45x2=90
Bumek [7]3 years ago
3 0

Answer:

B. 2 Hours

Explanation:

If you are going 45 miles per hour, you will travel 45 miles in 1 hour. It will take you 2 hours to travel 90 miles at a speed of 45 miles per hour.

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Please Help!!! I'll make Brainliest
il63 [147K]
Answer:

Float.

Explanation:

The formula we are going to use is <span>ρ=<span>mV</span></span> 
=> where ρ is the density in <span><span>gm</span>L</span>, m is the mass in grams, and V is the volume in <span>mL</span>. 

<span>ρ=<span>mV</span></span> 
<span>=<span>100150</span></span>
<span>=0.667</span>

The density of the wood is 0.667, therefore it will float on water. Hope this helps. 

7 0
3 years ago
Why are frames of reference important for motion
Fynjy0 [20]
Because frame of reference decides are your forces positive or negative. It is important for the direction of motion.
7 0
3 years ago
Please help me.
vesna_86 [32]

A) the tension in the string.

4 0
3 years ago
Read 2 more answers
Assume you have an ice cube and also a small rock that is the same size and shape as the ice cube. Predict what would happen if
Step2247 [10]

Answer: The ice cube would float on top of the water and the rock would sink to the bottom.

Explanation: The ice cube has a smaller density than the rock which allows the ice cube to float but makes the rock sink to the bottom of the glass of water.

7 0
3 years ago
The total energy of a block—spring system is 0.18 J. The amplitude is 14.0 cm and the maximum speed is 1.25 m/s. Find: (a) the m
algol13

a) The mass is 0.23 kg

b) The spring constant is 1.25 N/m

c) The frequency is 1.42 Hz

d) The speed of the block is 1.08 m/s

Explanation:

a)

We can find the mass of the block by applying the law of conservation of energy: in fact, the total mechanical energy of the system (which is sum of elastic potential energy, PE, and kinetic energy, KE) is constant:

E=PE+KE=const.

The potential energy is given by

PE=\frac{1}{2}kx^2

where k is the spring constant and x is the displacement. When the block is crossing the position of equilibrium, x = 0, so all the energy is kinetic energy:

E=KE_{max}=\frac{1}{2}mv_{max}^2 (1)

where

m is the mass of the block

v_{max}=1.25 m/s is the maximum speed

We also know that the total energy is

E=0.18 J

Re-arranging eq.(1), we can find the mass:

m=\frac{2E}{v_{max}^2}=\frac{2(0.18)}{(1.25)^2}=0.23 kg

b)

The maximum speed in a spring-mass system is also given by

v_{max} =\sqrt{\frac{k}{m}} A

where

k is the spring constant

m is the mass

A is the amplitude

Here we have:

v_{max}=1.25 m/s is the maximum speed

m = 0.23 kg is the mass

A = 14.0 cm = 0.14 m is the amplitude

Solving for k, we find the spring constant

k=\frac{v_{max}^2}{A^2}m=\frac{1.25^2}{0.14^2}(0.23)=18.3 N/m

c)

The frequency in a spring-mass system is given by

f=\frac{1}{2\pi}\sqrt{\frac{k}{m}}

where

k is the spring constant

m is the mass

In this problem, we have:

k = 18.3 N/m is the spring constant (found in part b)

m = 0.23 kg is the mass (found in part a)

Substituting and solving for f, we find the frequency of the system:

f=\frac{1}{2\pi}\sqrt{\frac{18.3}{0.23}}=1.42 Hz

d)

We can solve this part by using the law of conservation of energy; in fact, we have

E=PE+KE=\frac{1}{2}kx^2 + \frac{1}{2}mv^2

Where v is the speed of the system when the displacement is equal to x.

We know that the total energy of the system is

E = 0.18 J

Also we know that

k = 18.3 N/m is the spring constant

m = 0.23 kg is the mass

Substituting

x = 7.00 cm = 0.07 m

We can solve the equation to find the corresponding speed v:

v=\sqrt{\frac{2E-kx^2}{m}}=\sqrt{\frac{2(0.18)-(18.3)(0.07)^2}{0.23}}=1.08 m/s

#LearnwithBrainly

3 0
3 years ago
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