1) a) a particle rotates in a circle with a centripetal acceleration a=8.0m/s^2.

Question

1) a) a particle rotates in a circle with a centripetal acceleration a=8.0m/s^2.what is the value of a if (i) the radius is doubled without changing the particle speed?
b) (ii) the speed is doubled without changing the circle radius.

2) a 2.0kg block slides along a frictionless surface at 1.0m/s. a second block, sliding at a faster 4.0 m/s collides with the first from behind and sticks to it.the final velocity of the combined blocks is 2.0m/s.what is the mass of the second block.

3) 2 blocks(masses 8kg and 6kg) are pushed along a horizontal frictionless surface by a horizontal applied force F as shown.whatis the magnitude of the force that either of these blocks exerts o on the other if f=21N?

4) a block is released from rest at a point p 20 meters above ground level.it slides the frictionless tracks to a point q that is 12meters above ground level as shown .what is the speed of the block at point q.

5) a crane operator lowers a 5000N steel ball with a downward acceleration of 4m/s^2.calculate the tension in the cable.

6) a 1500kg car is travelling along a straight road at 20m/s. two sec.later its speed is 21m/s.what is the magnitude of the net force acting on the car during this time.

7) a 2.0kg book.is lying on a 0.75 m high table.you pick it up and place it on a bookshelf 2.3 m above the floor.
a) how much work does gravity fo on the book
b) how much work does your hand do on the book?

8) you are sitting in your physic vlass next to another student.60 m away.estimate the magnitude of the gravitational force between you.assume you each have a mass of 80 kg.
(G= 6.67x10^_11N_m^2/kg^2)

9) a car is travelling at 10m/s
a) how fast would the car need to go to double its kinectic energy
b)by what factor does the car s kinectic energy increase it its the speed is double to 20m/s?

10) how much energy can be stored in a spring with a spring constant of 500M/m if its maximum possible stretch is 20cm?

10) bob can throw a 500g rock with a speed of 30m/s.he moves his hand forward 1.0m while doing so.
a) how much gorce, assume to be constant, does bob apply to the rock?

b) how much work does bob do on the rock?

Explanation / Answer

1) i) a=8.0m/s^2 but centripetal acceleration ir w²r= 8 m/s²

if we double the radius r=2R so w²2R=16 m/s²

ii) the speed is doubled without changing the circle radius.

then w=2 W so (2 W )²r=2wr=16 m/s²

2) by the law of momentum conservation

M1U1+M2U2 =(M1+M2)V

M2 = 1 kg ans

4) V=(2.g(ho-hf) from conservation of energy we get this expresion

V=12.52m/s

5) m=5000/g = 510.2 kg

T-mg=-ma

T= 5000-510.2* 4

T= 2959.18N

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