9.2 - using F=ma

Question 1

what happens to an object if it’s acted upon by 2 unequal forces acting in opposite directions

Answer 1

it will accelerate in the direction of the larger force

Question 2

Car (m_c) pulling a trailer (m_t), (given masses + acceleration)

1- the equation for resultant force overall

2-the equation for the tension of the rope from the trailer

3- the equation for resultant force on the car

Answer 2

1) Resultant F = (m_c +m_t)a
2) T = m_t a
3) F = Resultant F - T

Question 3

Rocket (given mass + acceleration)

• the equation to calculate its thrust

Answer 3

T = mg + ma

(weight + resultant force)

Question 4

Lift problems

1- describe the acceleration and velocity when going up & down a lift when the tension in the cable < weight

2-describe the acceleration and velocity when going up & down a lift when the tension in the cable > weight

Answer 4

1) moving up; V > 0, a < 0

moving down; V < 0, a < 0

2) moving up; V > 0, a >0

moving down; V < 0, a > 0

Question 5

pully problems

1- what is the resultant force on m₁

2- what is the resultant force on m₂

3- combine the equations

Answer 5

1) m₁a = T - m₁g
2) m₂a = m₂g - T

(m1 + m2)a = m₂g - m₁g

Question 6

sliding down a slope

1-the equation to calculate the resultant force on the block

2-the equation to calculate the resultant force on the block with the addition of an engine force (F_e)

Answer 6

1) F = ma = mgsin(ø) - f
2) F = ma = F_e + mgsin(ø) - f