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3 years ago

How can you use your personal choices to exercise more safely

1 answer:

4 1

Not exercising in high-air pollution areas
limiting exercise in hot climates to the early morning and evening
using exercise equipment as it was designed to be used

Alizaha

2 years ago

which one????

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In being served, a tennis ball is accelerated from rest to a speed of 42.1 m/s. The average power generated during the serve is

hoa [83]

Answer:

Force F = 69.35 N

Explanation:

given data

Ball Initial speed u = 0

Ball Final speed v = 42.1 m/s

average power generate = 2920 W

solution

Power generate is express as

P= $\frac{W}{t}$ ..............1

here W is work done and t is time

and work w = F × d

P= $\frac{Fd}{t}$

and we know speed v = $\frac{d}{t}$

so here

Power P = F × v

put here value and we get force

Force F = $\frac{2920}{42.1}$

Force F = 69.35 N

8 0

3 years ago

The back wall of a home aquarium is a mirror that is a distance of 46.0 cm away from the front wall. The walls of the tank are n

monitta

Answer:

i know the questin but i got to try and find it

Explanation:

5 0

2 years ago

A billiard ball is dropped from a height of 64 feet. Use the position function s(t) = –16???? 2 + ????0???? + ????0 to answer th

Delicious77 [7]

Answer:

s(t) = -16*t^2 + 64

v(t) = -32*t

a(t) = -32 ft/s^2

v(t) = 64 ft/s ... At impact

Explanation:

Given:-

- The height of the billiard ball t = 0 , h = 64 ft.

- The position function of an object under gravity is given by:

s(t) = -16*t^2 + v_o*t + s_o

Find:-

a. Determine the position function s(t),

b. the velocity function v(t),

c. the acceleration function a(t).

d. What is the velocity of the ball at impact?

Solution:-

- To determine the position function we must initialize our problem and use the given general equation.

- s(t) is the position of the billiard ball from the ground at time t. So when t = 0, then s(t) = h. Hence, we have:

s(t) = s_o = h = 64 ft

- Similarly we know that v_o is the initial velocity of the ball. Since, the ball was dropped we say that the initial velocity v_o = 0. Hence, the position of the ball from ground is given by following expression:

s(t) = -16*t^2 + 64

- To find the velocity expression v(t) we will take the time derivative of the position expression s(t) as follows:

v(t) = d s(t) / dt

v(t) = -16*2*t + 0

v(t) = -32*t ft/s

- Similarly, the expression for acceleration a(t) is given by the time derivative of the velocity expression v(t) as follows:

a(t) = d v(t) / dt

a(t) = -32*t

a(t) = -32 ft/s^2

- The velocity of ball at impact can be determined by evaluating s(t) = 0 and find the value for time t. Then that time t can be substituted in the velocity expression v(t) for final velocity. Or we could use the following 3rd kinematic equation as follows:

v(t)^2 - 0^2 = 2*a(t)*s_o

v(t)^2 = 2*(32)*(64)

v(t) = 64 ft/s

- The ball has a velocity of 64 ft/s at impact!

6 0

3 years ago

A 12.70 g bullet has a muzzle velocity (at the moment it leaves the end of a firearm) of 430 m/s when rifle with a weight of 25.

Norma-Jean [14]

Answer:

2.1844 m/s

Explanation:

The principle of conservation of momentum can be applied here.

when two objects interact, the total momentum remains the same provided no external forces are acting.

Consider the whole system , gun and bullet. as an isolated system, so the net momentum is constant. In particular before firing the gun, the net momentum is zero. The conservation of momentum,

$0=m_{bullet}*v_{bullet} + m_{rifle}*v_{rifle} \\$

assume the bullet goes to right side and the gravitational acceleration =10 $ms^{-2}$

so now the weight of the rifle= $\frac{25}{10}$

$0=m_{bullet}*v_{bullet} + m_{rifle}*v_{rifle} \\\\0=(12.70*10^{-3}) *430ms^{-1} +(\frac{25}{10} )*v_{rifle} \\v_{rifle} =-2.1844ms^{-1}$

this is a negative velocity to the right side. that means the rifle recoils to the left side

3 0

2 years ago

The greater the mass is in an object, the higher resistance to a change in movement the object will have. Please select the best

Fofino [41]

This statement is true. The greater the mass is in an object, it is indeed the higher resistance to a change in movement the object will have. That only mean that the mass of an object and its resistance to change of movement is directly proportional.

3 0

3 years ago