A 5-kg object can move along the x axis. It is subjected to a force F in the pos

Question

A 5-kg object can move along the x axis. It is subjected to a force F in the positive x direction; a graph of F as a function of time t is shown below. Over the time the force is applied the change in the velocity of the object is: 0.8 m/s 1.1 m/s 1.6 m/s 2.3 m/s 4.0 m/s A student's life was saved in an automoblie accident because an airbag expanded in front of his head. If the car had not been equipped with an airbag, the windshield would have stopped the motion of his head in a much shorter time. Compared to the windshield, the airbag: causes a much smaller change in momentum exerts a much smaller impulse causes a much smaller change in kinetic energy exerts a much smaller force does much more work A 75-kg man is riding in a 30-kg cart at 2.0 m/s. He jumps off in such a way as to land on the ground with no horizontal velocity, the resulting change in speed of the cart is: zero 2.0 m/s 3.0 m/s 5.0 7.0 m/s

Explanation / Answer

1.

impulse = change in momentum = F*dt

m*dV = F*dt

dV = F*dt/m

dV = 4*2/5 = 1.6 m/sec

2.

The airbag exerts a much smaller force.

F = m*dV/dt

since airbag take more time than windshield, it will exerts much smaller force.

3.

momentum conservation:

Pf = Pi

m1*u1 + m2*u2 = m1*v1 + m2*v2

75*2 + 30*0 = 75*0 + 30*v2

v2 = 150/30 = 5 m/sec

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.