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3 years ago

Displacement is the change in velocity of an object. True or false

Physics

2 answers:

Elden [556K]3 years ago

7 0

Words less true are seldom if ever spoken.

Whitepunk [10]3 years ago

7 0

False, it is the change in distance. Chance in velocity would be Δv

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Running at maximum speed, it takes a boat times as long to go 10 miles upstream as it does to go 10 miles downstream. If the cur

Greeley [361]

Note: The question states the time to go upstream is a number of times (not explicitly written) the time to go downstream. We'll assume a general number N

Answer:

$\displaystyle v_b=\frac{N+1}{N-1}(4\ mph)$

Explanation:

Relative Speed

If a boat is going upstream against the water current, the true speed of motion is $v_b-v_w$ , being $v_b$ the speed of the boat and $v_w$ the speed of the water. If the boat is going downstream, the true speed becomes $v_b+v_w$ .

The question states the time to go upstream is a number of times N (not explicitly written) the time to go downstream. The speed of an object is computed as

$\displaystyle v=\frac{x}{t}$

Where x is the distance traveled and t the time taken for that. The time can be computed by

$\displaystyle t=\frac{x}{v}$

If $t_u$ is the time for the upstream travel and $t_d$ is the time for the downstream travel, then

$t_u=Nt_d$

Siince the same distance x= 10 miles is traveled in both cases:

$\displaystyle \frac{10}{v_b-v_w}=N\frac{10}{v_b+v_w}$

Simplifying and rearrangling

$v_b+v_w=N(v_b-v_w)$

Operating

$v_b+v_w=Nv_b-Nv_w$

Solving for $v_b$

$\displaystyle v_b=\frac{N+1}{N-1}v_w$

$If\ N=2,\ v_w=4\ mph$

$\displaystyle v_b=\frac{3}{1}(4)=12\ mph$

If N=3

$\displaystyle v_b=\frac{4}{2}v_w=2(4)=8\ mph$

We can use the required value of N to compute the speed of the boat as explained

7 0

4 years ago

hii, just wondering how to solve this? it’s simple scientific notation but my brain just isn’t functioning today so it’s be help

arlik [135]

Honestly just use desmos or mathyway

8 0

2 years ago

A football is thrown at an angle of 30.° above the horizontal. The magnitude of the horizontal

VladimirAG [237]

Answer:

1.53 s

Explanation:

Initially vertical component of velocity of the ball, uy = 7.5 m/s

Net displacement is vertical direction is zero, Δy =0

Use second equation of motion:

Δy = uy t + 0.5 a t²

Here, acceleration a = -g (g =9.8 m/s²)

Substitute all the values and solve for g

0 = 7.5 t -0.5 (9.8)t²

7.5 t = 4.9 t²

t = 1.53 s

8 0

3 years ago

Read 2 more answers

Whose law states that an induced current will create a magnetic field?

Zarrin [17]

Lenz law states the law

7 0

3 years ago

How many photons will be required to raise the temperature of 1.8 g of water by 2.5 k ?'?

tatyana61 [14]

Missing part in the text of the problem:
"Water is exposed to infrared radiation of wavelength 3.0×10^−6 m"

First we can calculate the amount of energy needed to raise the temperature of the water, which is given by
$Q=m C_s \Delta T$
where
m=1.8 g is the mass of the water
$C_s = 4.18 J/(g K)$ is the specific heat capacity of the water
$\Delta T=2.5 K$ is the increase in temperature.

Substituting the data, we find
$Q=(1.8 g)(4.18 J/(gK))(2.5 K)=18.8 J=E$

We know that each photon carries an energy of
$E_1 = hf$
where h is the Planck constant and f the frequency of the photon. Using the wavelength, we can find the photon frequency:
$\lambda = \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{3 \cdot 10^{-6} m}=1 \cdot 10^{14}Hz$

So, the energy of a single photon of this frequency is
$E_1 = hf =(6.6 \cdot 10^{-34} J)(1 \cdot 10^{14} Hz)=6.6 \cdot 10^{-20} J$

and the number of photons needed is the total energy needed divided by the energy of a single photon:
$N= \frac{E}{E_1}= \frac{18.8 J}{6.6 \cdot 10^{-20} J} =2.84 \cdot 10^{20} photons$

4 0

3 years ago