Page 25 - Pra U STPM 2021 Penggal 1 - Physics

Physics Term 1 STPM Chapter 2 Kinematics
5. An object is projected vertically from the top 8. (a) An object is projected with a speed of v at
of a building and it falls to the ground below. an angle θ to the horizontal. Derive the
Neglecting air resistance, which is the graph Cartesian equation for the trajectory of
of displacement-y against time t? the object.
A y C y (b) The figure below shows a boat approaching
a cliff of height 15.0 m at a constant
speed of 12.0 m s . A bullet is fired
-1
2 horizontally with a speed u when the boat
0
t
0 t
is 800 m from the cliff. The bullet strikes
the boat.
B y D y Bullet v
Cliff
15.0 m
0 t 0 t

800 m

6. A stone is thrown vertically upwards with (i) The bullet strikes the boat how many
an intial speed of 24.0 m s from the top of a seconds after been fired?
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tower 60.0 m above the ground. (ii) What is the distance of the boat
(a) Determine the speed of the stone when it from the cliff when it is struck by the
strikes the ground. bullet?
(b) Calculate the time taken to reach the (iii) Find the initial speed v of the bullet.
ground from the instant it is thrown. (iv) Determine the magnitude and
direction of the velocity of the bullet
7. A stone is thrown from a cliff which is at when it strikes the boat.
a height h above the water surface with a
velocity v at an angle θ to the horizontal as 9. A ball is kicked horizontally from a cliff of
shown in the figure below. After a time t, the height H with a velocity of 8.0 m s . The
–1
stone is at P(x,y). ball hits the water at an angle of 60° to the
y horizontal as shown in the diagram.
v
P(x, y) 8.0 m s –1
Clif
θ Cliff f
x
Cliff H
h 60º

R
(a) Neglecting air resistance, calculate
(i) speed of the ball when it hits the
(a) Write the expressions for the x- and water,
y-coordinates of P. (ii) H, the height of the cliff.
(b) The height h = 10.0 m, v = 12.0 m s and (b) If air resistance is not negligible, discuss
–1
θ = 60 . Calculate the horizontal distance the change in the angle that the ball hits
o
R. the water.

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