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3 years ago

8

How does hitting a ball with a tennis racquet involve action and reaction forces?

1 answer:

iragen [17]3 years ago

5 0

Answer:

In a tennis match, the racket exerts the action force on the ball and, as the ball hits it, it exerts an equal and opposite reaction force on the racket. The rocket launches because it pushes on the gas coming out the back end for the action force, while the gas pushes the rocket upward with a reaction force.

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Pete is driving down 7th Street. He drives 300 meters in 18 seconds. Assuming he does not speed up or slow down, what is his spe

Korolek [52]

Answer:

16.67m/s

Explanation:

Given parameters:

Distance Pete drove = 300m

Time taken = 18s

Unknown:

Speed = ?

Solution:

Speed is the distance traveled per unit of time.

It is mathematically expressed as;

Speed = $\frac{distance}{time}$

Insert the parameters and solve;

Speed = $\frac{300}{18}$ = 16.67m/s

3 0

3 years ago

The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have st

irina [24]

Complete Question:

The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have studied the change in length of the knee extensor tendon in sprinters and nonathletes. They find (on average) that the sprinters' tendons stretch 43 mm , while nonathletes' stretch only 32 mm . The spring constant for the tendon is the same for both groups, $31 {\rm {N}/{mm}}$ . What is the difference in maximum stored energy between the sprinters and the nonathlethes?

Answer:

$\triangle E = 12.79 J$

Explanation:

Sprinters' tendons stretch, $x_s = 43 mm = 0.043 m$

Non athletes' stretch, $x_n = 32 mm = 0.032 m$

Spring constant for the two groups, k = 31 N/mm = 3100 N/m

Maximum Energy stored in the sprinter, $E_s = 0.5kx_s^2$

Maximum energy stored in the non athletes, $E_m = 0.5kx_n^2$

Difference in maximum stored energy between the sprinters and the non-athlethes:

$\triangle E = E_s - E_n = 0.5k(x_s^2 - x_n^2)\\\triangle E = 0.5*3100* (0.043^2 - 0.032^2)\\\triangle E = 0.5*31000*0.000825\\\triangle E = 12.79 J$

4 0

3 years ago

What would be new resistance if length of conductor is doubled and thickness is halved <br>

nignag [31]

Answer:

The new resistance comes out to be = 4 times of original resistance .

6 0

3 years ago

What derived unit is used to measure the slope of the line in this graph?

Alexxx [7]

Answer:

g/cm³

Explanation:

From the question given above,

The y-axis is representing mass (g)

The x-axis is representing volume (cm³)

Unit of slope =?

Slope of a graph is simply defined as the change in y-axis divided by the change in x-axis. Mathematically it is expressed as:

Slope = change in y-axis (Δy)/change in x-axis (Δx)

Slope = Δy/Δx

Thus, with the above formula, we can obtain the unit used for measuring the slope as follow:

y-axis = mass (g)

x-axis = volume (cm³)

Slope =.?

Slope = Δy/Δx

Slope = mass (g) /volume (cm³)

Slope = g/cm³

Therefore, the derive unit used for measuring the slope is g/cm³

5 0

3 years ago

a stone is projected vertically up from the top of a tower 73.5m with velocity 24.5 m/s . find the time taken by the stone to re

hoa [83]

The stone's altitude at time $t$ is given by

$y=73.5\,\mathrm m+\left(24.5\dfrac{\rm m}{\rm s}\right)t-\dfrac g2t^2$

where $g=9.80\dfrac{\rm m}{\mathrm s^2}$ is the acceleration due to gravity. The stone reaches the ground when $y=0$ :

$0=73.5\,\mathrm m+\left(24.5\dfrac{\rm m}{\rm s}\right)t-\dfrac g2t^2\implies t=7.11\,\rm s$

6 0

3 years ago