HDE Section 2: Motion Flashcards
What is Newton’s first law?
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
What is Newton’s second law?
The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
What is Newton’s third law?
For every action, there is an equal and opposite reaction.
A lift and its load are raised by a cable, as shown in Figure 5.14.
1 If the total mass of the lift and its contents is 1.5 tonnes and the tension in the cable is 22.2 kN, calculate the acceleration of the lift.
2
a) Draw a free-body force diagram for a woman of mass 50 kg standing in the lift.
b) Calculate the normal contact force of the floor of the lift on her feet.
5ms^-2 upwards
740N
State Newton’s second law of motion.
F=MA
Show that 1 newton (N) is equivalent to 1 kgms^-2.
F=MA
N=kg ms^-2
Explain the difference between mass and weight.
Mass is a measure of the quantity of matter of a body while weight is the gravitational force acting upon the body. The mass of a body remains the same regardless of its position, whereas the weight will change in different regions of gravitational field strength.
Calculate the average braking force needed to bring a truck of mass 12 tonnes to rest from a speed of 20 m s in a distance of 40m.
6x10^4
A 50 kg mass is acted upon by forces of 30N and 40N which are at right angles to each other.
a) Calculate the resultant force acting on the mass.
b) Calculate the acceleration of the mass.
50
1
