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4 years ago

7

A strong-armed physics student throws a tennis ball vertically. The ball stays in the air for 5.5 seconds. Assuming the ball lef

t from the ground, how fast did it leave his hand?

1 answer:

Mila [183]4 years ago

4 0

Answer:

27.5 m/s

Explanation:

applying motion equations we can find the answer,

v = u + a*t

Let assume ,

u = starting speed(velocity)

v = Final speed (velocity)

t = time taken for the motion

a = acceleration

by the time of reaching the highest point subjected to the gravity , the speed should be equal to zero (only a vertical speed component is there)

for the complete motion it takes 5.5 s. that means to reach the highest point it will take 5.5/2 =2.75 seconds

we consider the motion upwards , in this case the gravitational acceleration should be negative in upwards (assume g=10 m/s2)

that is,

v = 0 , a = -10 $ms^{-2}$ , t =2.75

v = u + at

0 = u -10*2.75

u = 27.5 $ms^{-1}$

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Which would best be explained using Newton's Third Law?

Maksim231197 [3]

A)a gun moves backward while firing a bullet.

Explanation:

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3 years ago

A force platform is a tool used to analyze the performance of athletes measuring the vertical force that the athlete exerts on t

Phoenix [80]

Answer:

a. $I=981.34 N*s$

b. $v_f=3.96 m/s$

c. $v_{f1}=3.63m/s$

d. $y_f=0.673m$

Explanation:

Given: $m=67kg$ , $h=0.720m$ , $0$

a.

$I=\int\limits^{t_1}_{t_2} {F(t)} \, dt$

$F(t)=9200*t-11500t^2$

$I=\int\limits^{0.8s}_{0s}{9200*t-11500*t^2} \, dt$

$I=4600*t^2-3833.3*t^3|(0.80,0)$

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$I=981.34 N*s$

b.

$v_f^2=v_i^2+a*y'$

Starting from the rest

$v_f^2=0+2*9.8m/s^2*0.80s$

$v_f^2=15.68$

$v_f=\sqrt{15.68m^2/s^2}=3.96 m/s$

c.

$I_{total}=p_f$

$I_1-m*g*d=m*v_{f1}-m*v_f$

$981.34-67kg*9.8m/s^2*0.720=67.0kg*v_{f1}-67.0kg*(-3.96m/s)$

Solve to vf

$v_{f1}=3.63m/s$

d.

$v_f^2=v_i^2+2*a*y_f'$

$y_f'=v_i/2*a =(3.63m/s)^2/2*9.8m/s^2$

$y_f=0.673m$

7 0

3 years ago

The most likely theory of the formation of Earth's Moon is that it The most likely theory of the formation of Earth's Moon is th

Ann [662]

Answer:

Option (3)

Explanation:

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Thus, the correct answer is option (3).

4 0

4 years ago