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3 years ago

A gun has a muzzle speed of 150 m/s. Find two angles of elevation that can be used to hit a target 800m away.

Physics

1 answer:

lorasvet [3.4K]3 years ago

4 0

Answer:

Explanation:

u = 150 m/s

R = 800 m

The formula for the horizontal range is

$R=\frac{u^{2}Sin2\theta }{g}$

where, θ is angle of projection.

$800=\frac{150^{2}Sin2\theta }{9.8}$

Sin2θ = 0.348

2θ = 20.4°

θ = 10.2°

The range is same for the complementary angles.

So, the other angle is 90 - 10.2 = 79.8°

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A boy drops a ball from an observation tower. The ball hits the ground in 5.0 s. What is the ball's velocity at the time of impa

Orlov [11]

The answer is <span>C. 49 m/s

The kinetic equation is:
v2 = v1 + a * t

v1 - initial velocity
v2 - final velocity
a - gravitational acceleration
t - time

We know:
v2 = ?
v1 = 0 (in free fall
a = 9.8 m/s
t = 5

</span>v2 = v1 + a * t
v2 = 0 + 9.8 * 5
v2 = 0 + 49
v2 = 49 m/s

7 0

3 years ago

1. A sprinter races in the 100 meter dash. It takes him 10 second to reach the finish line

poizon [28]

Answer:

v = 10 m/s

Explanation:

Given that,

Distance covered by a sprinter, d = 100 m

Time taken by him to reach the finish line, t = 10 s

We need to find his average velocity. We know that velocity is equal to the distance covered divided by time taken. So,

v = d/t

$v=\dfrac{100\ m}{10\ s}\\\\v=10\ m/s$

Hence, his average velocity is 10 m/s.

6 0

3 years ago

The length of a simple pendulum is 0.81 mand the mass of the particle (the "bob") at the end of the cable is0.23 kg. The pendulu

Gemiola [76]

Answer:

$\displaystyle w=3.478\ rad/sec$

$M=0.0182\ J$

$v=0.398\ m/s$

Explanation:

<u>Simple Pendulum</u>

It's a simple device constructed with a mass (bob) tied to the end of an inextensible rope of length L and let swing back and forth at small angles. The movement is referred to as Simple Harmonic Motion (SHM).

(a) The angular frequency of the motion is computed as

$\displaystyle w=\sqrt{\frac{g}{L}}$

We have the length of the pendulum is L=0.81 meters, then we have

$\displaystyle w=\sqrt{\frac{9.8}{0.81}}$

$\displaystyle w=3.478\ rad/sec$

(b) The total mechanical energy is computed as the sum of the kinetic energy K and the potential energy U. At its highest point, the kinetic energy is zero, so the mechanical energy is pure potential energy, which is computed as

$U=mgh$

where h is measured to the reference level (the lowest point). Please check the figure below, to see the desired height is denoted as Y. We know that

$H+Y=L$

And

$H=L\ cos\alpha$

Solving for Y

$Y=L(1-cos\alpha )$

$Since\ \alpha=8.1^o, L=0.81\ m$

$Y=0.0081\ m$

The potential energy is

$U=mgh=0.23\ kg(9.8\ m/s^2)(0.0081\ m)$

$U=0.0182\ J$

The mechanical energy is, then

$M=K+U=0+U=U$

$M=0.0182\ J$

(c) The maximum speed is achieved when it passes through the lowest point (the reference for h=0), so the mechanical energy becomes all kinetic energy (K). We know

$\displaystyle K=\frac{mv^2}{2}$