1. A child and sled with a combined mass of 60 kg slide down a frictionless slop

Question

1. A child and sled with a combined mass of 60 kg slide down a frictionless slope (hill). if the sled starts from rest and has a speed of 5 m/s at the bottom:

a. Determine the kinetic energy of the system just as it reaches the bottom of the hill.

b. What is the height of the hill?

2. Two objects are connected by a light string passing over a light, frictionless pulley as shown below. The 7 kg object is released from rest at a point 6 m above the floor

a. What is the potential energy of the 7 kg object before it is released?

b. Determine the speed of each object when the two passes each other.

c. Determine the speed and the kinetic energy of each object at the moment the 7 kg object hits the floor.

3. A 100 g bullet moving at 500 m/s strikes a 6 kg wooden block lying at rest in a frictionless plane. The bullet penetrates through the block, leaving from the opposite side at 300 m/s.

a. What is the momentum of the bullet before the impact?

b. What is the momentum of the wooden block before the impact?

c. Determine the momentum and the kinetic energy of the bullet just after it leaves the wooden block.

d. Does the wooden block move after the impact? If yes, calculate the velocity; if no, justify your answer.

4. A 5 kg object moving to the right at 10 m/s overtakes and collides (perfectly) elastically with a 2 kg object moving in the same direction at 5 m/s:

a. Determine the momentum of each object before the collision

b. Find the velocity of each object after the collision.

c. Calculate the kinetic energy transferred from the 5kg object to the 2kg object as a result of the collision.

1. A child and sled with a combined mass of 60 kg slide down a frictionless slope (hill). if the sled starts from rest and has a speed of 5 m/s at the bottom: a. Determine the kinetic energy of the system just as it reaches the bottom of the hill. b. What is the height of the hill? 2. Two objects are connected by a light string passing over a light, frictionless pulley as shown below. The 7 kg object is released from rest at a point 6 m above the floor a. What is the potential energy of the 7 kg object before it is released? b. Determine the speed of each object when the two passes each other. c. Determine the speed and the kinetic energy of each object at the moment the 7 kg object hits the floor. 3. A 100 g bullet moving at 500 m/s strikes a 6 kg wooden block lying at rest in a frictionless plane. The bullet penetrates through the block, leaving from the opposite side at 300 m/s. a. What is the momentum of the bullet before the impact? b. What is the momentum of the wooden block before the impact? c. Determine the momentum and the kinetic energy of the bullet just after it leaves the wooden block. d. Does the wooden block move after the impact? If yes, calculate the velocity; if no, justify your answer. 4. A 5 kg object moving to the right at 10 m/s overtakes and collides (perfectly) elastically with a 2 kg object moving in the same direction at 5 m/s: a. Determine the momentum of each object before the collision b. Find the velocity of each object after the collision. c. Calculate the kinetic energy transferred from the 5kg object to the 2kg object as a result of the collision.

Explanation / Answer

1a)KE=0.5mv^2=0.5*60*5^2=750N

b)Gain in Kinetic energy=loss in potential energy.

750=60*g*h

h=750/(60*9.81)=1.27m

2a)U=mgh=7*9.81*6=412J

b)Cannot find this since distance between objects is not visible in the figure.

c)Conserving energy,

412=4*9.81*6+0.5*(4+7)*v^2

v=5.67m/s

3a)p=mu=0.1*500=50kgm/s

b)0

c)p=mv=0.1*300=30kgm/s

d)Conserving momentum,

50+0=30+6v

v=3.33m/s

4a)p of 5 kg=5*10=50kgm/s

p of 2kg =2*5=10kgm/s

Let the final velocities be x and y both in the original direction,

50+10=5x+2y

Also, since collision is elastic,

(10-5)=(y-x)

Solving for x and y,

x=7.15m/s

y=12.14m/s

c)KE transferred=0.5*2*12.14^2-0.5*2*5^2=122.4J

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

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