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Andrej [43]
3 years ago
14

A rocket initially at rest accelerates at a rate of 90 m/s 2 for 0.7 min. What is its speed at the end of this time? Answer in u

nits of m/s.
Physics
1 answer:
alexira [117]3 years ago
7 0

Answer:

Final speed of the rocket, v = 3780 m/s

Explanation:

It is given that,

Initial speed of the rocket, u = 0 (at rest)

Acceleration of the rocket, a=90\ m/s^2

Time taken, t = 0.7 min = 42 s

We need to find the speed at the end of this time. It can be calculated using first equation of motion as :

v=u+at

v=90\times 42

v = 3780 m/s

So, the speed of the rocket at the end at the end of 0.7 minutes is 3780 m/s. Hence, this is the required solution.

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A bullet is shot horizontally from shoulder height (1.5 m) with an initial speed 200 m/s. (a) How much time elapses before the b
daser333 [38]

Answer:

<h2>a) Time elapsed before the bullet hits the ground is 0.553 seconds.</h2><h2>b) The bullet travels horizontally 110.6 m</h2>

Explanation:

a)  Consider the vertical motion of bullet

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 0 m/s

        Acceleration, a = 9.81 m/s²  

        Displacement, s = 1.5 m      

     Substituting

                      s = ut + 0.5 at²

                      1.5 = 0 x t + 0.5 x 9.81 xt²

                      t = 0.553 s

      Time elapsed before the bullet hits the ground is 0.553 seconds.

b) Consider the horizontal motion of bullet

We have equation of motion s = ut + 0.5 at²

        Initial velocity, u = 200 m/s

        Acceleration, a = 0 m/s²  

        Time, t = 0.553 s      

     Substituting

                      s = ut + 0.5 at²

                      s = 200 x 0.553 + 0.5 x 0 x 0.553²

                      s = 110.6 m

      The bullet travels horizontally 110.6 m

6 0
3 years ago
This exercise uses the radioactive decay model. After 3 days a sample of radon-222 has decayed to 58% of its original amount. (a
Vadim26 [7]

Answer: a) 3.85 days

b) 10.54 days

Explanation:-

Expression for rate law for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

where,

k = rate constant  = ?

t = time taken for decomposition  = 3 days

a = let initial amount of the reactant  = 100 g

a - x = amount left after decay process  = \frac{58}{100}\times 100=58g

First we have to calculate the rate constant, we use the formula :

Now put all the given values in above equation, we get

k=\frac{2.303}{3}\log\frac{100}{58}

k=0.18days^{-1}

a) Half-life of radon-222:

t_{\frac{1}{2}}=\frac{0.693}{k}

t_{\frac{1}{2}}=\frac{0.693}{0.18}=3.85days

Thus half-life of radon-222 is 3.85 days.

b) Time taken for the sample to decay to 15% of its original amount:

where,

k = rate constant  = 0.18days^{-1}

t = time taken for decomposition  = ?

a = let initial amount of the reactant  = 100 g

a - x = amount left after decay process  = \frac{15}{100}\times 100=15g

t=\frac{2.303}{0.18}\log\frac{100}{15}

t=10.54days

Thus it will take 10.54 days for the sample to decay to 15% of its original amount.

3 0
3 years ago
A 4.9-MeV (kinetic energy) proton enters a 0.28-T field, in a plane perpendicular to the field. Part APart complete What is the
BartSMP [9]

Answer:

r=1.14m

Explanation:

\theta is the angle between the velocity and the magnetic field. So, the magnetic force on the proton is:

F_m=qvBsen\theta\\F_m=qvBsen(90^\circ)\\F_m=qvB

A charged particle describes a semicircle in a uniform magnetic field. Therefore, applying Newton's second law to uniform circular motion:

F_m=F_c\\qvB=F_c(1)

F_c is the centripetal force and is defined as:

F_c=m\frac{v^2}{r}

Here v is the proton's speed and r is the radius of the circular motion. Replacing this in (1) and solving for r:

qvB=\frac{mv^2}{r}\\r=\frac{mv^2}{qvB}\\r=\frac{mv}{qB}

Recall that 1 J is equal to 6.242*10^{12}MeV, so:

4.9MeV*\frac{1J}{6.242*10^{12}MeV}=7.85*10^{-13}J

We can calculate v from the kinetic energy of the proton:

K=\frac{mv^2}{2}\\\\v=\sqrt{\frac{2K}{m}}\\v=\sqrt{\frac{2(7.85*10^{-13}J)}{1.67*10^{-27}kg}}\\v=3.06*10^{7}\frac{m}{s}

Finally, we calculate the radius of the proton path:

r=\frac{mv}{qB}\\r=\frac{1.67*10^{-27}kg(3.06*10^{7}\frac{m}{s})}{1.6*10^{-19}C(0.28T)}\\r=1.14m

8 0
4 years ago
A force of 30 N is applied to an object with a mass of 15 kg. What is the resulting acceleration?
svet-max [94.6K]

Answer:

We know that Force = mass × acceleration

By substituting the values we get,

30 N = 15 kg × a (where a is acceleration)

Or we can write it as

15 kg × a = 30 N

Transposing 15 to RHS,

a = 30 ÷ 15 m/s²

Therefore, acceleration = 2 m/s²

pls give brainliest for the answer

5 0
3 years ago
Read 2 more answers
I need help please with this question
Sergio039 [100]

Explanation:

it's B =) hhggusucvgaugcavsjssnd

3 0
3 years ago
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