1. A car accelerates from 32km/hr to 65 km/hr over 200m. What is the magnitude of the force acting on it? Assume the car has a mass if 980 kg

2. Justin just does not have it anymore. He demands to throw a fast ball but his catcher says to throw a curve because his fast ball is not fast enough. Justin insists to throw a fast ball and does. His catcher takes off his glove and catches the ball bare handed.
a. Determine the impulse required to stop a 0.153-kg baseball moving at 25.7m/s (3 points)

b. If this impulse is delivered to the ball in 0.015 seconds, then what is magnitude of the force acting between the bare hand and the ball? (2 points)

3. A 102 kg bungee jumper jumps off a bridge on Mars. The bridge is 405 m above the river at its center point. The bungee cord spring constant is 44 N/m, the cords relaxed length is 130 m and its length is 235 m when the jumper stops falling. What is the T

Question

contestada

Respuesta :

aristocles aristocles · Answer 1 · 2019-01-14T07:05:32+01:00

#1

As per kinematics we know that

[tex]v_f^2 - v_i^2 = 2 a s[/tex]

here we know that

[tex]v_f = 65 km/h = 18.1 m/s[/tex]

[tex]v_i = 32 km/h = 8.9 m/s[/tex]

[tex]s = 200 m[/tex]

now we will have

[tex]18.1^2 - 8.9^2 = 2(a)(200)[/tex]

[tex]a = 0.62 m/s^2[/tex]

Now by Newton's II law

[tex]F = ma[/tex]

[tex]F = 980 \times 0.62 = 608.6 N[/tex]

#2

part a)

Impulse = change in momentum

[tex]I = m(v_f - v_i)[/tex]

given that

m = 0.153 kg

v = 25.7 m/s

now we have

[tex]I = 0.153(25.7 - 0) = 3.93 kg m/s[/tex]

Part b)

As per Newton's II law we know that

[tex]F = \frac{\Delta P}{\Delta t} = \frac{I}{\Delta t}[/tex]

as we know that

[tex]\Delta t = 0.015 s[/tex]

[tex]F = \frac{3.93}{0.015} = 262.14 N[/tex]