WEEK 1 – 4’s EXERCISES
Deadline: 10AM, 15th Mar, 2025
Q1. A ball is initially thrown upward along a y axis, with a velocity of 20.0 m/s at the edge
of a 50-meters high buiding.
a. How long does the ball reach its maximum height?
b. What is the ball’s maximum height?
c. How long does the ball take to return to its release point? And its velocity at that point?
d. What are the velocity and position of the ball at t = 5s
e. How long does the ball take to hit the ground? And what is its velocity when it strikes the
ground?
(Given g = 9.8 m/s2)
Consider using
and
Q2. A projectile is shot from the edge of a building 115m with an intial
speed of 65.0 m/s at an angle of 35o with the horizontal (the figure).
Determine:
a. The max height of the projectile above the building
b. The projectile velocity when it strikes the ground at point A
c. Point A from the base of the building (distance X)
Q3. Three astronauts propelled by jet backpacks, push and guide a 460
kg asteroid toward the spaceship, exerting the forces (in fig), with F1 = 46 N, F2 =
60 N, F3 = 57 N, θ1 = 30o , θ2 = 60o. What is the asteroid acceleration
a. In unit-vector notation
b. As a magnitude
c. A direction relative to the positive direction of the x axis
Q4. In the fig. 1, a constant horizontal force is applied to block A, which pushes
against block B with a 15.0 N force directed horizontally to the right. In fig. 2, the
same force is applied to block B, now block A pushes on block B with a 10.0 N force direced horizontally
to the left. The blocks have a combined mass of 12.0 kg.
a. What are the magnitude of their acceleration in (1) fig. 1 and (2) fig. 2
b. What are the masses mA and mb
c. If we know Fa = 25 N, ma = 4.8 kg and mb = 7.2 kg. Determine contact forces between the blocks in
Fig. 3 and Fig. 4
Hints
For part (a):
o Use Newton’s Second Law: F=ma
o Consider the entire system as a single object to determine the acceleration.
o Identify the net force acting on both blocks in each figure.
For part (b):
o Use the contact forces given in Fig. 1 and Fig. 2 to set up equations for individual blocks.
o Consider the forces acting on each block separately and solve for mA and mB.
For part (c):
o Again, apply F=ma to each block separately in Fig. 3 and Fig. 4.
o The contact force between the blocks is the force that one block exerts on the other.
o Pay attention to the direction of forces in each scenario.
Q5. A person is lifting a 20 kg weight using their biceps muscle as a lever. The distance from the elbow
joint to the hand holding the weight is 35 cm, while the distance from the elbow joint to the biceps insertion
point is 6 cm.
(a) Calculate the mechanical advantage of the biceps lever system.
(b) Determine the force required from the biceps muscle to lift the weight.
Q6. An object of 9 kg is moving horizontally at a speed of 16.0 m/s. Find the work done on the block to
decrease its speed to 5.0 m/s
Q7. A wheel of rotational inertia 10.0 kg.m2. Starting from 2 rad/s and accelerates under a constant torque of
5.0 N.m for 6.0 s. Find the rotational kinetic energy of the wheel at the end of 6.0 s.
Q8. There’s a 0.4 kg block of slippery ice that slides along a frictionless track from point a to point b. The ice
block travels through a total distance of 8.4 cm along the track, and a net vertical distance of 1.2 cm. How
much work is done on the ice block by the gravitational force during the slide? (given g = 9.81 m/s-2)
Hint: Since the gravitational force Fg is a conservative force, you can choose a simple path to calculate the
work done by Fg (for example, construct a horizontal and vertical path from a to b)
Q9. A dog weighed 24 kg is staying at rest when a 8.0 N force pushed its body. Compute the work done by
the force in
a. The first, the second, and the fifth seconds
b. The instantaneous power due to the force at the end of the fifth second.
THE END