Physics
section
1. Dawn will travel 4,800,000,000 km in 8 years.
speed
= distance ÷ time
|
Dawn’s average speed in km per year
will be
A 384 000 000
B 600 000 000
C 38 400 000 000
D 60 000 000 000
B 600 000 000
C 38 400 000 000
D 60 000 000 000
(Total
1 mark)
2. Julia
and Alec are investigating how the motion of an object changes with different
size forces.
They produce this velocity-time graph for the
motion of a motorcycle.
What is the acceleration of the motorcycle?
A 4 m/s2 a = (v-u)/t = (12-4)/2 = 8/2 = 4m/s2
B 6 m/s2
C 8 m/s2
D 12 m/s2
B 6 m/s2
C 8 m/s2
D 12 m/s2
(Total
1 mark)
3.
force
= mass × acceleration
|
The space probe has a mass of 1200 kg.
Out in space, it accelerates at 0.00008 m/s2.
The force producing this acceleration is (I know force is measure in N so A and C are wrong. I also know that 1200 x 0.00008 will be less than 9600 so D is wrong)
Out in space, it accelerates at 0.00008 m/s2.
The force producing this acceleration is (I know force is measure in N so A and C are wrong. I also know that 1200 x 0.00008 will be less than 9600 so D is wrong)
A 0.096 kg
B 0.096 N F=ma = 1200 x 0.00008 = 0.096N
C 9600 kg
D 9600 N
B 0.096 N F=ma = 1200 x 0.00008 = 0.096N
C 9600 kg
D 9600 N
(Total
1 mark)
4. (a) Stewart is a keen racing cyclist. Charlie
uses a touring bike to
cycle to school.
Their bikes are shown in the diagram.
Their bikes are shown in the diagram.
Stewart and Charlie have the same mass, and produce the same driving forces on their
bikes.
(i) Which
cyclist is able to produce the greater
acceleration when they start moving?
Suggest why.
Suggest why.
Cyclist
....Stewart
Reason
the racing bike has less mass
(2)
(ii) Stewart
is able to reach a higher
maximum speed on his bike.
Suggest two reasons why. (notice the diagram, without the lines I have drawn the profile to the air resistance is not obvious)
Suggest two reasons why. (notice the diagram, without the lines I have drawn the profile to the air resistance is not obvious)
1
Stewart is able to offer a lower profile so there is
less drag
2
.The tyres on the racing bike are thinner so there is
less friction between them and the road
(Note you cannot use less mass again) (2)
(b) One day Stewart and Charlie decided to have
a bike race. Stewart started
some time after Charlie, because he felt his bike was better suited to
racing than Charlie’s bike.
The graph shows how the velocity
changed with time for both cyclists.
(i) How
many seconds after Charlie
did Stewart start?
time
= ..............2..............................................
s
(1)
(ii) How
many seconds did it
take Stewart to reach the same
speed as Charlie?
time
= .......................10 – 2 = 8.....................................
s
(1)
(iii) Use the graph to calculate Charlie’s acceleration.
a = (v-u)/t = (4-0)/10 = 0.4 m/s-2
acceleration
= ......................................... m/s2
(2)
(iv) What
is the difference between
velocity and speed? Make sure you
use the words scalar
and vector in your
answer.
Velocity is the rate of change of displacement and has
magnitude and direction. It is a vector
Speed is the distance travelled in 1 second. It has magnitude
only. Speed is scalar
(2)
(Total
10 marks)
5. The
diagram shows the forces
on a car travelling along a level
road.
(a) How can you tell that the car is accelerating forwards?
The forward driving force is greater than the backward resistive
force. There is a resultant forward force. When a force acts on an object it
accelerates in the direction of the force.
(1)
(b) The
total mass of the car is 850
kg.
Calculate the acceleration of the car.
F = ma. Resultant
force = 950N – 550N = 400N
Rearranging a = F/m = 400/850 = 0.47 m/s2
(3)
(c) Explain
how the horizontal forces
on the car change when
the driver takes her foot off
the accelerator and applies
the brake.
When the driver takes her foot off the accelerator the
driving force drops to zero. As air resistance is proportional to the velocity the
resistive force will fall as the velocity falls. The backward forces increase
when the driver applies the brakes.
(note – the question only asks you to comment on the
forces not the acceleration or the velocity)
(3)
(Total
7 marks)
