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2 years ago

An object accelerates from rest with a constant acceleration of 2 m/s2. How far will it have moved after 9s?

Physics

1 answer:

maw [93]2 years ago

5 0

As per the question the, the initial velocity of object [u] =0

The acceleration of the block $[a]=2\ m/s^2$

The time taken by the object[t] = 9 s.

We are asked to calculate the distance travelled by the object in that time.

As per equation of kinematics we know that-

$s=\ ut+\frac{1}{2} at^2$

Here s is the distance travelled by the object.

$=0*9+\frac{1}{2} 2*[9]^2\ m$

$=81\ m$ [ans]

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A 91.5 kg football player running east at 2.73 m/s tackles a 63.5 kg player running east at 3.09 m/s. what is their velocity aft

Ierofanga [76]

2.88 m/s is the velocity afterward.

Explanation:

By using the law of conservation of momentum

Initial momentum = final momentum

$\mathrm{m}_{1} \mathrm{u}_{1}+\mathrm{m}_{2} \mathrm{u}_{2}=\left(\mathrm{m}_{1}+\mathrm{m}_{2}\right) \times \mathrm{v} \text { equation }(1)$

$\mathrm{m}_{1}=91.5 \mathrm{kg} \text { is the mass of the first player }\mathrm{m}_{2}=63.5 \mathrm{kg}$

$\mathrm{m}_{2}=63.5 \mathrm{kg} \text { is the mass of the second player }$

$\mathrm{u}_{1}=2.73 \mathrm{m} / \mathrm{s} \text { is the initial velocity of the first player (choosing east as positive direction) }$

$\mathrm{u}_{2}=3.09 \mathrm{m} / \mathrm{s} \text { is the initial velocity of the second player }$

v = is their combined velocity afterwards

Solving equation (1) for v

$V=\frac{m_{1} u_{2}+m_{2} u_{2}}{m_{1}+m_{2}}$

$\mathrm{V}=\frac{(91.5 \times 2.73)+(63.5 \times 3.09)}{91.5+63.5}$

$\mathrm{V}=\frac{(249.7+196.2)}{155}$

$\mathrm{V}=\frac{445.9}{155}$

V = 2.88 m/s

Therefore the velocity afterward is <u>2.88 m/s</u>.

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2 years ago

A student sits motionless on a stool that can turn friction-free about its vertical axis (total rotational inertia I). The stude

vampirchik [111]

Answer:

Explanation:

The problem can be solved with the help of conservation of angular momentum.

Initial angular momentum

= I₁ω₀

When wheel is turned by 180 degree , its angular momentum becomes

- I₁ω₀ .

So total angular momentum

= - I₁ω₀ . + I W where W is angular velocity of student .

Applying conservation of angular momentum

=I₁ω₀= - I₁ω₀ +I W

2 I₁ω₀ = I W

W = 2 I₁ω₀ / I

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2 years ago

Which nucleus completes the following equation?

siniylev [52]

A is the answer I really don’t know the answer to that but if u can u can help me on my work

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2 years ago

Read 2 more answers

A 30-m-long rocket train car is traveling from Los Angeles to New York at 0.5c when a light at the center of the car flashes. Wh

Novosadov [1.4K]

Given that,

Distance =30 m

speed = 0.5c

(A). We need to find the bell and siren simultaneous events for a passenger seated in the car

According to given data

The distance travelled by the light to reach either side of the rocket train car is same.

So, The two events are simultaneous and the bell and siren are the simultaneous events for a passenger seated in the car.

(B). We need to calculate time interval between the events

Using formula of time dilation

$\Delta t=\dfrac{\Delta t'}{\sqrt{1-\dfrac{v^2}{c^2}}}$ .....(I)

Where, $\delta t'$ = proper time

$\delta t$ = time interval between the events

The time interval between the events measured in a reference frame

The proper time in this case is

$\Delta t'=\Delta t_{1}-\dfrac{v\Delta x}{c^2}$

For the second interval,

Put the value of $\Delta t'$ in the equation (I)

$\Delta t_{2}=\dfrac{\Delta t_{1}-\dfrac{v\Delta x}{c^2}}{\sqrt{1-\dfrac{v^2}{c^2}}}$

Put the value in the equation

$\Delta t_{2} = \dfrac{0-\dfrac{0.5c\times30}{c^2}}{\sqrt{1-\dfrac{0.5^2c^2}{c^2}}}$

$\Delta t_{2}=\dfrac{-15}{3\times10^{8}\sqrt{1-0.25}}$

$\Delta t_{2}=-5.77\times10^{8}\ s$

Negative sign shows the siren rings before the bell ring.

Hence, (A). Yes, the bell and siren are simultaneous events.

(B). The siren sounds before the bell rings.

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2 years ago

One end of a piano wire is wrapped around a cylindrical tuning peg and the other end is fixed in place. The tuning peg is turned

liq [111]

Answer:

$T = 3183 N$

Explanation:

When the screw is turned by two turns then change in the length of the wire is given as

$\Delta L = 2(2\pi r)$

$\Delta L = 4\pi r$

$\Delta L = 4(\pi)(1.0 mm)$

$\Delta L = 12.56 mm$

now we know by the formula of Young's modulus

$Y = \frac{T/A}{\Delta L/L}$

so we have

$T = \frac{AY \Delta L}{L}$

$T = \frac{\pi (0.55 \times 10^{-3})^2(2.0 \times 10^{11})(12.56 \times 10^{-3})}{0.75}$

$T = 3183 N$

3 0

2 years ago