You have seen that two objects with opposite charges attract each other, and two objects with the same charge repel each other.
1 answer:
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The final velocity of the man standing on roller skates with the ball caught, after it is thrown at him at a speed of 5 m/s, is 0.042 m/s.
The velocity of the man with the ball can be calculated by conservation of linear momentum:
Where:
: is the mass of the ball = 0.5 kg
: is the <u>mass</u> of the man = 59.5 kg
: is the initial velocity of the <u>ball</u> = 5 m/s
: is the <u>initial velocity</u> if the <u>man</u> = 0 (he is standing still)
: is the final velocity of the <u>ball</u> =?
: is the <u>final velocity</u> of the <u>man</u> =?
Since the man catches the ball, his final velocity is the same that the final ball's velocity, so:
Therefore, the velocity of the man with the ball is 0.042 m/s.
Learn more about the conservation of linear momentum here:
I hope it helps you!
Answer:
She must be launched with a speed of 74.2 m/s.
Explanation:
Hi there!
The equations of the horizontal component of the position vector and the vertical component of the velocity vector are the following:
x = v0 · t · cos θ
vy = v0 · sin θ + g · t
x = horizontal distance traveled at time t.
v0 = initial velocity.
t = time.
θ = launching angle.
vy = vertical component of the velocity vector at time t.
g = acceleration due to gravity (-9.8 m/s²).
To just cross the 520-m gap, the maximum height of the flight must be reached halfway of the gap at 260 m horizontally (see attached figure).
When she is at the maximum height, her vertical velocity is zero. So, when x = 260 m, vy = 0. Using both equations we can solve the system for v0:
x = v0 · t · cos θ
Solving for v0:
v0 = x/ (t · cos θ)
Replacing v0 in the second equation:
vy = v0 · sin θ + g · t
0 = x/(t·cos(56°)) · sin(56°) + g · t
0 = 260 m · tan (56°) / t - 9.8 m/s² · t
9.8 m/s² · t = 260 m · tan (56°) / t
t² = 260 m · tan (56°) / 9.8 m/s²
t = 6.27 s
Now, let's calculate v0:
v0 = x/ (t · cos θ)
v0 = 260 m / (6.27 s · cos(56°))
v0 = 74.2 m/s
She must be launched with a speed of 74.2 m/s.
