92

Physics Work,Power & Energy Level: High School

A rifle weighs 40.N and its barrel is 0.80 m long. It shoots a 28 g bullet , which leaves the barrel with a speed of 380 m/s (muzzle velocity) after being uniformly accelerated . What is the average reaction force acting on the rifle ? (using the method)

a). kinematics and f = ma

b) energy method

c) momentum-impulse method and how to check each method which gives the value of F .


91

Physics Work,Power & Energy Level: High School

A 3kg ball of putty moving at 1 m/s collides and sticks to a 2 kg ball initially at rest . The putty and ball then moves with a momentum of :

4 N s

1 N s

3 N s

2 N s

0 N s


90

Physics Work,Power & Energy Level: High School

In an inelastic collision , the final total momentum is

the same as the initial momentum

less than the initial momentum

none of these

more than the initial momentum

The same as the initial momentum

89

Physics Work,Power & Energy Level: High School

A bullet,of mass 20 g , traveling at 350 m/s , strikes a steel plate at an angle of 30 degree with the plane of the plate . It ricochets off at the same angle , at a speed of 320 m/s . what is the magnitude of the impulse that the wall gives to the bullet ?

0.30 N s

300 N s

0.52 N s

6.7 N s


88

Physics Work,Power & Energy Level: High School

A plane , flying horizontally , releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the centre of mass of the bomb fragments, just after the explosion

is zero

moves along a parabolic path

moves vertically

moves horizontally

moves along a parabolic path

87

Physics Work,Power & Energy Level: High School

Two car suffer a head on collision . What is conserved in the collision ?

none of these

kinetic energy

momentum

mechanical energy and momentum

momentum

86

Physics Work,Power & Energy Level: High School

How fast must a 10.5 g bullet be traveling when it strikes a ballistic pendulum that consists of a block of wood of mass 3.0 kg that is suspended by a cord ? The bullet gets embedded in the block . The block rises by 0.22m after the impact.

85

Physics Work,Power & Energy Level: High School

The momentum of the particle is proportional to the square of its velocity

True

False

p = m v = p x v False

84

Physics Work,Power & Energy Level: High School

A particle of mass M is joined to a fixed point A by a string (massless) of length L. Initially the string is slack and the mass moves with constant speed v_0 along a straight line . When the mass reaches a distance of L from A the string becomes taut and the particle goes into a circular path around A. (there is no gravity in this problem).

a. What conservation law is applicable in this situation and why

b. Calculate the ratio of the initial to final kinetic energy if they are not the same


83

Physics Work,Power & Energy Level: High School

A 2.00 kg block of wood moves up an inclined plane at a constant velocity . If the angle is 30 degrees and the coefficient of the kinetic friction between the block and the plane is 0.435 . What is the magnitude of the frictional force ? what is the value of the force (F) going upward to move the block at a constant velocity ? if the block has moved 1.50 m up the incline , what is the amount of work done in the process ? what is the change in the potential energy in the process ?

82

Physics Work,Power & Energy Level: High School

A 70 kg athlete climbs a rope in the gymnasium at a constant speed of 0.700 m/s . What is the average power (in watts) developed in the process ? if the athlete climbs 5 meters , what is the amount of work done ? How much time does it take to climb the 5 meters ?

81

Physics Work,Power & Energy Level: High School

20.0 gram (better make it 0.0200 kg ) bullet is fired horizontally at a slab of wood that is 3.00 cm (better make it 0.0300 m) thick . The bullet had and initial velocity of 300 m/s . The bullet exits the other side of the wood with a velocity of 280 m/s . What is the change in kinetic energy of the bullet in this process ? How much work is done on the bullet by the wood ? What is the average force of the wood on the bullet ? What is the average acceleration of the bullet while traveling the slab of wood ?

80

Physics Work,Power & Energy Level: High School

You are going around a circular loop on a roller coaster and precisely at the top of the loop you are moving at a speed of 15.65 m/s and you feel weightless . How tall is the loop if rest on the ground ? (50m)

79

Physics Work,Power & Energy Level: High School

A 680.000 kg vehicle is negotiating a uniform turn of radius R = 50000 m at uniform speed v = 56.500 km/h . If the coefficient of static friction was not enough . Suppose it turns out to be 0.27 on some day when the road is wet or covered with ice . What angle would one hope the curve was banked at in order to make the turn safely without slipping ?( 11.68 degree)

77

Physics Work,Power & Energy Level: High School

An object is moving in a circular path of radius 1 m with a uniform speed of 1.0 x 106 m/s . The acceleration of the object has a magnitude of :

1.0 x 10^3m/s^2

0

1.0 x 10^6 m/s^2

1.0 x 10^12m/s^2


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