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Jet001 [13]
4 years ago
12

A toy rocket is fired vertically into the air from the ground at an initial velocity of 80 feet per second. Find the time it wil

l take for the rocket to return to ground level
Physics
1 answer:
miskamm [114]4 years ago
8 0

Answer: 16.3 seconds

Explanation: Given that the

Initial velocity U = 80 ft/s

Let's first calculate the maximum height reached by using third equation of motion.

V^2 = U^2 - 2gH

Where V = final velocity and H = maximum height.

Since the toy is moving against the gravity, g will be negative.

At maximum height, V = 0

0 = 80^2 - 2 × 9.81 × H

6400 = 19.62H

H = 6400/19.62

H = 326.2

Let's us second equation of motion to find time.

H = Ut - 1/2gt^2

Let assume that the ball is dropped from the maximum height. Then,

U = 0. The equation will be reduced to

H = 1/2gt^2

326.2 = 1/2 × 9.81 × t^2

326.2 = 4.905t^2

t^2 = 326.2/4.905

t = sqrt( 66.5 )

t = 8.15 seconds

The time it will take for the rocket to return to ground level will be 2t.

That is, 2 × 8.15 = 16.3 seconds

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Motion of a dog is shown in this velocity vs time graph.
Tcecarenko [31]

Answer:

8,3

Explanation:

3 0
3 years ago
A girl walks 5km due north,then in the direction of 60° of northeast towards her final destination.If the magnitude of her resul
storchak [24]

Answer:

4.2 km

Explanation:

A triangle is a polygon with three sides and three angles. There are different types of triangles such as isosceles triangle, scalene triangle, equilateral triangle and right angled triangle.

Sine rule states that for a triangle with angles A,B and C and corresponding opposite sides a, b, and c, the following formula holds:

\frac{a}{sin(A)}=\frac{b}{sin(B)}=\frac{c}{sin(C)}

Let the starting point be A, hence the side opposite to the  angle = a = distance travelled in north east direction.

Let the point of 60° of northeast be B = 90° + (90° - 60°) = 120°, hence the side opposite to the  angle = b = resultant displacement = 8 km.

Let C be the endpoint, hence the side opposite to the  angle = c = distance travelled north = 5 km

Using sine rule:

\frac{b}{sin(B)}=\frac{c}{sin(C)}  \\\\\frac{8}{sin(120)}=\frac{5}{sin(C)}  \\\\sin(C)=\frac{5*sin(120)}{8} =0.5412\\\\C=sin^{-1}(0.5412)=32.8^o\\\\

∠A + ∠B + ∠C = 180° (sum of angle in a triangle)

∠A + 120 + 32.8 = 180

∠A = 27.2°

\frac{b}{sin(B)}=\frac{a}{sin(A)}  \\\\\frac{8}{sin(120)}=\frac{a}{sin(27.2)}  \\\\a=\frac{8*sin(27.2)}{sin(120)} \\\\a=4.2\ km

Therefore she travelled 4.2 km in the north east direction

5 0
3 years ago
An artillery shell is fired with an initial velocity of 300 m/s at 55.0° above the horizontal. It explodes on a mountainside 42.
GuDViN [60]

Answer:

x=7227

y=1678

(7227,1678)

Explanation:

Ok, check the picture I attached you, because of the problem don't give us aditional information, let's asume that the projectile is fired from an initial position x=0 and y=0. Now let's use projectile motion equations, but firs let's find the initial velocity components in x-axis and y-axis:

v_ox=v_o*cos(\theta_o)=300*cos(55)=172.0729309m/s

v_oy=v_o*sin(\theta_o)=300*sin(55)=245.7456133m/s

Now, let's find the x coordinate with this equation:

x-x_o=x-0=x=v_ox*t=172.0729309*42=7227.063098m

Finally asumming a gravity constant g=9.8, let's find the y coordinate with the next equation:

y-y_o=y-0=y=v_oy*t-\frac{1}{2}*g*t^{2} =(245.7456133*42)-\frac{42^{2} *9.8}{2}

y=10321.31576-8643.6=1677.71576m

8 0
3 years ago
A boat travels north at a rate of 25.0 kilometers per hour (km/hr) relative to the current of the river. The current of the rive
USPshnik [31]

Answer:yes

Explanation:yes

4 0
3 years ago
What is the mass of an object if a net force of 18 N causes it to accelerate at 15 m/s^2?
trasher [3.6K]

Answer:

1.2 kg

Explanation:

F = 18N

a = 15 m/s^2

F = ma

18 = 15m

m = 1.2 kg

3 0
3 years ago
Read 2 more answers
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