<h3><u>Answer;</u></h3>
C) He could injure or pull a muscle.
<h3><u>Explanation</u>;</h3>
- <em><u>When muscles are stretched the muscle fibers are temporary lengthened. Muscles have a unique ability to undergo contraction and lengthening since they are elastic.</u></em>
- <em><u>When the muscles are warm they are more elastic, therefore, warming up the muscles is very important for the purpose of avoiding injuries.</u></em> Ir is important to engage in moderate cardiovascular warm-up prior to stretching, which increases the blood flow to the active and thus avoiding injuries to the muscles.
- Stretching muscles when they are cold may bring injuries or cause muscle pulls, which are painful.
Answer:
1250 N
Explanation:
length of wrench = 20 cm = 0.2 m
Write the length of wrench in vector form
r = 0.2 j metre
Direction of force= 
Let the magnitude of force is F
So, write the force in vector form
F = F 
torque, T = 150 Nm
Torque = T = r x F

F = 1250 N
Thus, the magnitude of force is 1250 N.
Answer:
The answer to your question is
a) t = 2.55 s
b) t = 5.5 s
Explanation:
Data
vo = 25 m/s
h = 2 m
g = 9.81 m/s
Formula
t = -(vo)/g
a)
t = -(25)/9.81
t = 2.55 s
b)
Tt = 2t
Tt = 2(2.55)
Tt = 5.1 s
Time in the last 10 m
10 = 25t + (1/2)(9.81)t²
Simplify
10 = 25t 4.91t²
4.9t² + 25t - 10 = 0
Solve the equation using an online calculator
t₁ = 0.37 s t₂ = -5.47 s
The correct answer is t₁, t₂ is incorrect because there are no negative answers.
Total time = 5.1 + 0.37
= 5.5 s
The frequency is how many per second:
(6 swings)/(30 sec) = (6/30) swing/sec = 0.2 per sec = 0.2 Hz .
The period is how long each one takes, or seconds per swing.
It's exactly the flip of frequency.
So we could just take the frequency, flip it, and find 1 / 0.2 ,
but let's do it the long way:
(30 sec) / (6 swings) = (30/6) sec/swing = 5 seconds .
Answer:
(a) 7.315 x 10^(-14) N
(b) - 7.315 x 10^(-14) N
Explanation:
As you referred at the final remark, the electron and proton undergo a magnetic force of same magnitude but opposite direction. Using the definition of magnetic force, a cross product must be done. One technique is either calculate the magnitude of the velocity and magnetic field and multiplying by sin (90°), but it is necessary to assure both vectors are perpendicular between each other ( which is not the case) or do directly the cross product dealing with a determinant (which is the most convenient approach), thus,
(a) The electron has a velocity defined as: ![\overrightarrow{v}=(2.4x10^{6} i + 3.6x10^{6} j) \frac{[m]}{[s]}\\\\](https://tex.z-dn.net/?f=%5Coverrightarrow%7Bv%7D%3D%282.4x10%5E%7B6%7D%20i%20%2B%203.6x10%5E%7B6%7D%20j%29%20%5Cfrac%7B%5Bm%5D%7D%7B%5Bs%5D%7D%5C%5C%5C%5C)
In respect to the magnetic field; ![\overrightarrow{B}=(0.027 i - 0.15 j) [T]](https://tex.z-dn.net/?f=%5Coverrightarrow%7BB%7D%3D%280.027%20i%20-%200.15%20j%29%20%5BT%5D)
The magnetic force can be written as;
![\overrightarrow{F} = q(\overrightarrow{v} x \overrightarrow{B})\\ \\\\\overrightarrow{F}= q \left[\begin{array}{ccc}i&j&k\\2.4x10^{6}&3.6x10^{6}&0\\0.027&-0.15&0\end{array}\right]](https://tex.z-dn.net/?f=%5Coverrightarrow%7BF%7D%20%3D%20q%28%5Coverrightarrow%7Bv%7D%20x%20%5Coverrightarrow%7BB%7D%29%5C%5C%20%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%20q%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Di%26j%26k%5C%5C2.4x10%5E%7B6%7D%263.6x10%5E%7B6%7D%260%5C%5C0.027%26-0.15%260%5Cend%7Barray%7D%5Cright%5D)
Bear in mind
thus,
![\overrightarrow{F}= q \left[\begin{array}{ccc}i&j&k\\2.4x10^{6}&3.6x10^{6}&0\\0.027&-0.15&0\end{array}\right]\\\\\\\overrightarrow{F}= q(2.4x10^{6}* (-0.15)- (0.027*3.6x10^{6}))\\\\\\\overrightarrow{F}= -1.6021x10^{-19} [C](-457200) [T]\frac{m}{s}\\\\\overrightarrow{F}=(7.3152x10^{-14}) k [\frac{N*m/s}{C*m/s}]\\\\|F|= \sqrt{ (7.3152x10^{-14})^{2}[N]^2 *k^{2}}\\\\F=7.3152x10^{-14} [N]](https://tex.z-dn.net/?f=%5Coverrightarrow%7BF%7D%3D%20q%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Di%26j%26k%5C%5C2.4x10%5E%7B6%7D%263.6x10%5E%7B6%7D%260%5C%5C0.027%26-0.15%260%5Cend%7Barray%7D%5Cright%5D%5C%5C%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%20q%282.4x10%5E%7B6%7D%2A%20%28-0.15%29-%20%280.027%2A3.6x10%5E%7B6%7D%29%29%5C%5C%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%20-1.6021x10%5E%7B-19%7D%20%5BC%5D%28-457200%29%20%5BT%5D%5Cfrac%7Bm%7D%7Bs%7D%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%287.3152x10%5E%7B-14%7D%29%20k%20%5B%5Cfrac%7BN%2Am%2Fs%7D%7BC%2Am%2Fs%7D%5D%5C%5C%5C%5C%7CF%7C%3D%20%5Csqrt%7B%20%287.3152x10%5E%7B-14%7D%29%5E%7B2%7D%5BN%5D%5E2%20%2Ak%5E%7B2%7D%7D%5C%5C%5C%5CF%3D7.3152x10%5E%7B-14%7D%20%5BN%5D)
Note: The cross product is operated as a determinant. Likewise, the product of the unit vector k is squared and that is operated as dot product whose value is equal to one, i.e, 
(b) Considering the proton charge has the same magnitude as electron does, but the sign is positive, thus
![\overrightarrow{F}= q \left[\begin{array}{ccc}i&j&k\\2.4x10^{6}&3.6x10^{6}&0\\0.027&-0.15&0\end{array}\right]\\\\\\\overrightarrow{F}= q(2.4x10^{6}* (-0.15)- (0.027*3.6x10^{6}))\\\\\\\overrightarrow{F}= 1.6021x10^{-19} [C](-457200) [T]\frac{m}{s}\\\\\overrightarrow{F}=(-7.3152x10^{-14}) k [\frac{N*m/s}{C*m/s}]\\\\|F|= \sqrt{ (-7.3152x10^{-14})^{2}[N]^2 *k^{2}}\\\\F=-7.3152x10^{-14} [N]](https://tex.z-dn.net/?f=%5Coverrightarrow%7BF%7D%3D%20q%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Di%26j%26k%5C%5C2.4x10%5E%7B6%7D%263.6x10%5E%7B6%7D%260%5C%5C0.027%26-0.15%260%5Cend%7Barray%7D%5Cright%5D%5C%5C%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%20q%282.4x10%5E%7B6%7D%2A%20%28-0.15%29-%20%280.027%2A3.6x10%5E%7B6%7D%29%29%5C%5C%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%201.6021x10%5E%7B-19%7D%20%5BC%5D%28-457200%29%20%5BT%5D%5Cfrac%7Bm%7D%7Bs%7D%5C%5C%5C%5C%5Coverrightarrow%7BF%7D%3D%28-7.3152x10%5E%7B-14%7D%29%20k%20%5B%5Cfrac%7BN%2Am%2Fs%7D%7BC%2Am%2Fs%7D%5D%5C%5C%5C%5C%7CF%7C%3D%20%5Csqrt%7B%20%28-7.3152x10%5E%7B-14%7D%29%5E%7B2%7D%5BN%5D%5E2%20%2Ak%5E%7B2%7D%7D%5C%5C%5C%5CF%3D-7.3152x10%5E%7B-14%7D%20%5BN%5D)
Note: The cross product is operated as a determinant. Likewise, the product of the unit vector k is squared and that is operated as dot product whose value is equal to one, i.e, 
Final remarks: The cross product was performed in R3 due to the geometrical conditions of the problem.