Newton's laws

Question 1

Newton’s third law

Answer 1

Newton’s Third Law of Motion states that the force exerted by one body on a second body is equal in magnitude, opposite in direction and of the same type as the force simultaneously exerted by the second body on the first body.

Question 2

4 conditions for 2 forces to be an action reaction pair

Answer 2

1. Act on different bodies (A on B and B on A)
2. Same type
3. Equal in magnitude
4. opposite in direction

Question 3

Newton’s First Law of Motion

Answer 3

Newton’s first law of motion states that a body will stay at rest, and a body in motion will continue to move at constant velocity, unless acted on by a resultant external force

Question 4

Using Newton’s First Law, if an object is at rest, and Fnet=0

Answer 4

Object remains at rest

Question 5

Using Newton’s First Law, if an object is moving with constant velocity and Fnet=0,

Answer 5

Object continues moving at constant v

Question 6

Conditions for an object in equilibrium

Answer 6

1. Resultant force acting on body is 0
2. Resultant torque acting about any axis of rotation must be zero

Question 7

Momentum eqn

Answer 7

p (Kgm/s or Ns)=mv

Question 8

Newton’s Second Law of Motion

Answer 8

Newton’s Second Law of Motion states that the rate of change of momentum of a body is proportional to the resultant force acting on the body and is in the same direction as the resultant force

Question 9

eqn for Newton’s second law

Answer 9

Fnet=ma

Question 10

When an elevator is at rest,
1. acceleration____
2. Fnet____
3.N(=/>/<)W
4. Apparent weight( =/>/<) True Weight

Answer 10

When an elevator is at rest,
1. acceleration=0
2. Fnet=0
3.N=W
4. Apparent weight=True Weight

Question 11

When an elevator is experiencing upward acceleration,
1. acceleration____
2. Fnet____
3.N(=/>/<)W
4. Apparent weight( =/>/<) True Weight

Answer 11

When an elevator is experiencing upward acceleration,
1. acceleration directed upwards
2. Fnet directed upwards
3.N>W
4. Apparent weight> True Weight

Question 12

State the possible directions and changes in speed for an elevator experiencing upward acceleration

Answer 12

1. Lift going up, speed increase
2. Lift going down, speed decrease (deceleration downwards=acceleration upwards)

Question 13

When an elevator is experiencing downward acceleration,
1. acceleration____
2. Fnet____
3.N(=/>/<)W
4. Apparent weight( =/>/<) True Weight

Answer 13

When an elevator is experiencing downward acceleration,
1. acceleration directed downwards
2. Fnet directed downwards
3.N<W
4. Apparent weight<True Weight

Question 14

State the possible directions and changes in speed for an elevator experiencing downward acceleration

Answer 14

1. Lift going down, speed increase
2. Lift going up, speed decrease (deceleration upwards=acceleration downwards)