Monday, February 29, 2016

Year 9 - Physics - 29-2-16

Weight & Gravitational acceleration

In all of the questions below you should assume that on the Earth’s surface a mass of 1 kg weighs 10 N.
That is the gravitational field strength is 10 N / kg.

1.         Calculate the weight of a boy of mass 80 kg.
2.         Calculate the weight of a girl of mass 110 kg.
3.         Calculate the weight of a apple of mass 100 g.
4.         Calculate the weight of a car of mass 1300 kg.
5.         Calculate the weight of a feather of mass 0.1 g.

6.         What is the mass of a boy of weight 600 N?
7.         What is the mass of a girl of weight 480 N?
8.         What is the mass of an orange of weight 2 N?
9.         What is the mass of a car of weight 11 k N?
10.       What is the mass of a piece of paper of weight 0.02 N?

For questions 11 to 20:
Repeat the above questions but this time for when the various bodies on the surface of the Moon where gravity is 1/6 th the strength of that on the Earth’s surface.
That is a mass of 1 kg would now weigh 1.7 N
That is the gravitational field strength is 1.7 N / kg.

For the questions below you are on the Earth’s surface again. Assume there is no air resistance.

21.       Calculate the downward acceleration of a boy of mass 50 kg jumping off a wall.
22.       Calculate the downward acceleration of a girl of mass 70 kg jumping off a wall.
23.       Calculate the downward acceleration of a stone of mass 400 g being dropped off a wall.
24.       Calculate the downward acceleration of a feather of mass 0.05 g being dropped off a wall.
25.       Calculate the downward acceleration of a elephant of mass 2000 kg falling off a wall.

For questions 26 to 30:
Repeat the above (questions 21 to 25) this time for the surface of the Moon.

31.       If in questions 21 to 25 air resistance was present, which of your answers would be significantly different?
32.       Why would you not need to worry about air resistance with questions 26 to 30?



Equations to use:

weight = mass x gravitational field strength

acceleration = force / mass




 Force = mass x acceleration

1.         Calculate the force needed to accelerate a car of mass 1000 kg by 3 m/s2.
2.         Calculate the force needed to accelerate a bicycle of mass 20 kg by 4 m/s2.
3.         Calculate the force needed to accelerate a car of mass 1500 kg by 5 m/s2.
4.         Calculate the force needed to accelerate a bus of mass 4000 kg by 2 m/s2.
5.         Calculate the force needed to accelerate a train of mass 20 000 kg by 0.5 m/s2.

6.         Calculate the force needed to accelerate a toy car of mass 100 g by 6 m/s2.
7.         Calculate the force needed to accelerate a ball of mass 200 g by 15 m/s2.
8.         Calculate the force needed to accelerate a bat of mass 500 g by 4 m/s2.
9.         Calculate the force needed to accelerate a bee of mass 2 g by 20 m/s2.
10.       Calculate the force needed to accelerate a flee of mass 0.005 g by 30 m/s2.

11.       Calculate the acceleration of a car of mass 1000 kg when driven by a force of  20 000 N.
12.       Calculate the acceleration of a bus of mass 5000 kg when driven by a force of  30 000 N.
13.       Calculate the acceleration of a ball of mass 0.3 kg when driven by a force of  21 N.
14.       Calculate the acceleration of a train of mass 30 000 kg when driven by a force of  15 000 N.
15.       Calculate the acceleration of a toy car of mass 50 g when driven by a force of  4 N.

16.       Calculate the mass of a car if a force of 15000 N causes it to accelerate by 5 m/s2.
17.       Calculate the mass of a bus if a force of 20000 N causes it to accelerate by 4 m/s2.
18.       Calculate the mass of a ball if a force of  50 N causes it to accelerate by 100 m/s2.
19.       Calculate the mass of a toy car if a force of 2 N causes it to accelerate by 10 m/s2.
20.       Calculate the mass of a car if a force of 15 kN causes it to accelerate by 10 m/s2.

21.       Calculate the force needed to accelerate a train of mass 60 000 kg by 0.25 m/s2.
22.       Calculate the acceleration of a car of mass 800 kg when driven by a force of 24 k N.
23.       Calculate the mass of a car if a force of 30 k N causes it to accelerate by 2 m/s2.
24.       Calculate the force needed to accelerate a ball of mass 150 g by 12 m/s2.
25.       Calculate the acceleration of a toy car of mass 40 g when driven by a force of 0.8 N.

26.       Calculate the force required to accelerate a car of mass 1000 kg from rest to 12 m/s in 3 seconds.
27.       Calculate the force required to decelerate a car of mass 1500 kg from 20 m/s to rest in 4 seconds.
28.       A car of mass 2000 kg is driven by a force of 40 kN for 5 seconds; how much does its speed change?
29.       If a bus accelerates from 10 m/s to 15 m/s in 10 seconds with a force of 3 kN what is its mass?
30.       What force is exerted on a ball of mass 100g if it accelerates from rest to 30 m/s in 3 seconds?


Equations to use:

force = mass x acceleration

acceleration = force / mass

mass = force / acceleration

acceleration = change in velocity / time taken



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