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Agata [3.3K]
3 years ago
10

A man claims that he can hold onto a 16.0-kg child in a head-on collision as long as he has his seat belt on. Consider this man

in a collision in which he is in one of two identical cars each traveling toward the other at 59.0 mi/h relative to the ground. The car in which he rides is brought to rest in 0.05 s.
Find the magnitude of the average force needed to hold onto the child.
N
Physics
1 answer:
Anna007 [38]3 years ago
5 0

Answer:

F = -8440.12 N

the magnitude of the average force needed to hold onto the child is 8440.12 N

Explanation:

Given;

Mass of child m = 16 kg

Speed of each car v = 59.0 mi/h = 26.37536 m/s

Time t = 0.05s

Applying the impulse momentum equation;

Impulse = change in momentum

Ft = ∆(mv)

F = ∆(mv)/t

F = m(∆v)/t

Where;

F = force

t = time

m = mass

v = velocity

Since the final speed of the car is zero(at rest) then;

∆v = 0 - v = -26.37536 m/s

Substituting the given values;

F = 16×-26.37536/0.05

F = -8440.1152 N

F = -8440.12 N

the magnitude of the average force needed to hold onto the child is 8440.12 N

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A 10 m long uniform beam weighing 100 N is supported by two ropes at the ends. If a 400 N person sits at 2.0 m from one end of t
Naddik [55]

Answer:

T1 = 130N, T2 = 370N

Explanation:

In order for the system to be at rest, the sum of all forces must be zero and the torque around a point on the beam must be zero.

1. forces:

Let tension in rope 1 be T1 and in rope 2 be T2:

ma = T1 + T2 - 100N - 400N = 0

(1) T1 + T2 = 500N

2. torque around the center point of the beam:

τ = r x F = 5*T1 + 3*400N - 5*T2 = 0

(2) T1 - T2 = -240N

Solving both equations:

T1 = 130N

T2 = 370N

3 0
4 years ago
A composite material is to be designed with epoxy (Em 3.5 GPa) and unidirectional fibers. The longitudinal elastic modulus of th
LenKa [72]

Answer:

Minimum elastic modulus of fiber = 455.64 GPa

Explanation:

Contents of composite material = Epoxy and Unidirectional fibers

Elastic modulus of epoxy = 3.5 GPa

Elastic modulus of composite material = 320 GPa

Volume fraction of fiber = 70 %

Volume fraction of epoxy = 100 - 70 = 30%

Elastic modulus of composite material = 3.5 x 0.3 + Elastic modulus of fiber x 0.7 = 320

0.7 x Elastic modulus of fiber = 320 - 1.05 = 318.95

Elastic modulus of fiber = 455.64 GPa

Minimum elastic modulus of fiber = 455.64 GPa

5 0
3 years ago
A runner moves 2.88 m/s north. She accelerates at 0.350 m/s^2 at a -52.0 angle. At the point in the motion where she is running
MrRissso [65]

The runner has initial velocity vector

\vec v_0=\left(2.88\dfrac{\rm m}{\rm s}\right)\,\vec\jmath

and acceleration vector

\vec a=\left(0.350\dfrac{\rm m}{\mathrm s^2}\right)(\cos(-52.0^\circ)\,\vec\imath+\sin(-52.0^\circ)\,\vec\jmath)

so that her velocity at time t is

\vec v=\vec v_0+\vec at

She runs directly east when the vertical component of \vec v is 0:

2.88\dfrac{\rm m}{\rm s}+\left(0.350\,\dfrac{\rm m}{\mathrm s^2}\right)\sin(-52.0^\circ)\,t=0\implies t=10.4\,\rm s

It's not clear what you're supposed to find at this particular time... possibly her position vector? In that case, assuming she starts at the origin, her position at time t would be

\vec x=\vec v_0t+\dfrac12\vec at^2

so that after 10.4 s, her position would be

\vec x=(10.1\,\mathrm m)\,\vec\imath+(17.2\,\mathrm m)\,\vec\jmath

which is 19.9 m away from her starting position.

8 0
4 years ago
Read 2 more answers
Is the Force balanced or unbalanced?
Alexus [3.1K]

Answer:

1. balanced

2. unbalanced

3. balanced

4. balanced

5. unbalanced

6. unbalanced

7. unbalanced

8. balanced

9. unbalanced

10. unbalanced

11. unbalanced

12. balanced

3 0
3 years ago
15 POINTS !!!
nirvana33 [79]

#1

As per work energy theorem work done by all forces must be equal to change in its kinetic energy

so correct answer will be

W_{net} = change in kinetic energy


#2

Torque is defined as

\tau = r \times F

\tau = rFsin\theta

so here torque will be maximum when applied force is perpendicular to the rod

so first figure of rod is correct for maximum torque


#3

When car makes turn then its passengers moves outwards which is due to the property of inertia because due to this property passengers has tendency to move in same direction and hence it feels to move outwards

So correct answer will be

<em>inertia</em>


#4

As per energy conservation we can say

initial potential energy = final kinetic energy

PE = KE

KE = mgH

KE = 0.5(9.8)(0.5)

KE = 2.5 J

7 0
4 years ago
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